Muktol

I mean no offence, but you might want to read http://www.mtgvault.com/muktol/decks/how-to-build-a-deck/
Short version is that you have to many cards and way to many different cards to make a deck that allows you to play continuous and stable.

Half colored mana costs, such as {R/B}, count as red AND black, no mater which colors you use to cast it. Also cards with different colors in it's ability text are forbidden, e.g. "Cranial Plating", tough an colorles artefact, may only be used in decks with at least a black commander.

Some suggestions, based on my own monoR Goblin commander deck (http://www.mtgvault.com/muktol/decks/edh-krenko-mob-boss/)
Dragon Throne of Tarkir; Thousand-Year Elixir; Konda's Banner
Arms Dealer; Battle Squadron; Bloodmark Mentor; Furystoke Giant; Goblin Assassin; Goblin Bushwhacker;Moggcatcher
Hordeling Outburst; Ruination
Homeward Path; Valakut, the Molten Pinnacle

Greetings
Muktol

Though no defender, "Hedron Crab" is a very good card for mill decks.
"Traumatize" is far to expensive and ineffective for it's effect, I would add some carddraw (e.g. "Visions of Beyond")

Greetings
Muktol

OK, budget (single cardprice below 2$) suggestions for a Phenax deck:
Hover Barrier; Jace's Phantasm; King Macar, the Gold-Cursed; Knacksaw Clique; Wall of Frost; Wrexial, the Risen Deep; Silent Arbiter; Dragon's Eye Savants; Dream Stalker; Drift of Phantasms; Glacial Wall; Murmuring Phantasm
Sword of the Paruns; Slagwurm Armor; Illusionist's Bracers; Magewright's Stone
Freed from the Real; Intruder Alarm (~3,5$ but it's worth every cent); Pemmin's Aura; Second Wind;
Triton Tactics

To make full use of Phenax, I would add some more defenders like Wall of Frost, and Enchantments or Artifacts which allow you to untap your creatures and thus use them again. "Intruder Alarm" would be the best one to get because it allows you to untap (and thus tap and mill) your creatures with every creature your opponent plays.
At the moment your deck is rather spell-heavy, and I would stick with Mirko.
Question is, do you want to play this singe or multiplayer?

A Phenax deck would look totally different: Walls with high toughness, enchantments like "Intruder Alarm" or "Freed from the real", equipment which increases toughness, and so on.
Also Phenax is not a real budged card, which might be OK for a commander, but that's the reason why I didn't add him in my suggestions.

I would focus on +X/+0 equipment because cards like "Kor Duelist" and "Kitesail Apprentice" normally don't care for their toughness. (e.g. Machete vs Bonesplitter)

Some suggestions, I tried to stay budget friendly ;)
Undercity Informer, Belltower Sphinx, Gomazoa, Duskmantle Guildmage, Consuming Aberration (Non Budget), Yixlid Jailer, Belltower Sphinx, Shriekgeist, Augur of Bolas
Profane Memento
Extract from Darkness, Paranoid Delusions
Nephalia Drownyard

Greetings
Muktol

*like*
"Slippery Bogle" could be an alternative to "Squadron Hawk"
I'm also really missing "Ethereal Armor" and perhaps "Forced Adaptation"

Greetings
Muktol

I would focus on some cheaper equipment when using Kor's that benefit from being equipped.

Some suggestions, based on my own monoW kor equipment deck (http://www.mtgvault.com/muktol/decks/monow-kor-equipment/)
Bone Saw, Bonesplitter, Cranial Plating, Swiftfoot Boots
Etched Champion, Ornithopter
Darksteel Citadel

Greetings
Muktol

Blood Artis vs Kalastria Highborn, well that's a personal question. Drawback on Kalastria is that you have to keep that {B} free, on the other hand, she is a 2/2 and can block and attack with your other vamps.

Well the Blade IS slow, but considering the high number of removalspells many decks play there's always something dying, and 2 +1/+1 counter per dying creature for cc2...I gave it a try, and was happy with it.

The point why Dismember is such an extreme popular card is that you can pay it with phyrexian mana, but you don't have to. And -X/-X cards are very effective as they allow you to remove indestructible creatures and stop regenerating creatures.

looking good *like*

Nevertheless, some suggestions, based on my monoB vampire deck (http://www.mtgvault.com/muktol/decks/vampire-onslaught-revised/)
"Blade of the Bloodchief"
"Bloodghast" (Especially in combination with searchlands like "Evolving Wilds" or "Verdant Catacombs")
"Kalastria Highborn"...2 lifepoint means 1/10th of your opponents total life
"Vampire Hexmage"...at least sideboard material against planeswalkers
"Dismember"...big brother of "Disfigure", can be played with phyrexian mana
"Tragic Slip"...indestructible gods? well not any longer with this spell

Greetings
Muktol

The thing I personally dislike on "Door of Destinies" is that it comes into play and does...nothing. If you don't manage to successfully cast some spells of your tribe it's a dead card. "Coat of Arms" may help your opponent, but that depends on the decks you're going after. If you play in an enviroment that uses many tribal decks, then something else may be better. If your opponents use whatever is available, they might not benefit from it like you will.

Jace is a very good mill card, but as you explained, you want to focus on your vampires (beatdown) and only run mill to keep pressure on your opponents and as distraction (at last that is what I understood). So the only thing Jace does here is buy you time, one to two rounds, depending on the situation.

As for some further cards, try to do some testgames (I use Magic Workstation for this, though you can only play against the same deck in the unregistred version).

It does. So basically you want a vampire beatdown commander deck, with a little mill 'splashed' in.

Then you could think about removing some of the following cards:
"Ashiok, Nightmare Weaver", "Jace, Memory Adept"
"The Chain Veil", "Glaring Spotlight", "Door of Destinies" (Replace with e.g. "Coat of Arms")
"Falkenrath Exterminator", "Jin-Gitaxias, Core Augur", "Nemesis of Reason", "Urabrask the Hidden", "Wrexial, the Risen Deep"
"Curse of the Bloody Tome", "Death Denied", "Cruel Ultimatum", "Glimpse the Unthinkable", "Paranoid Delusions"

I also would recommend to do some testgames and see which cards work and which don't, or which you have in your hand, but can't play, and so on.

A little deck description would help us to help you. Especially in commander it's not that easy to look over 100 (or more in this case) cards and instantly know what the builder had in mind.

There are e.g. several ways to mill your opponent: Stay defensive and use spells, aggressive creatures like "Mirko Vosk, Mind Drinker", use "Phenax, God of Decept" and high toughness creatures, and so on. Also it's makes a big difference if you want to play this deck in multiplayer games or just one on one.

Greetings
Muktol

Personally I don't like "Door of Destinies" because it comes into play and does...nothing. If you don't manage to play goblin spells (and doubling goblins with Krenko doesn't count towards this) then it's a dead card. Could be replaced with "Konda's Banner" or e.g. "Obelisk of Urd"
"Goblin Rabblemaster" is also a card that I personally dislike, because sometimes you have to sit still and wait, but this guy here forces you to attack.
"Goblin Wizard" depends on your mana-curve. If you focus on low-mana creatures then it shouldn't be needed.
"Reckless One": From what I experienced while playing with my goblin deck is that if you manage to get Krenko and some tokens out then it's GG for your opponent, and all those 'power and toughness equal number of goblins' creatures are pure overkill. I still have one or two of those in my deck though.
"Goblin Goon": Cheap 6/6 without any further abilities, thus can easily be blocked by a 1/1 and all it's damage will vanish
"Goblin Grappler"

Greetings
Muktol

I would remove 10-16 vampires to add some support spells (carddraw, removal, equipment, and so on) and 2-4 more lands, depending on your new mana-curve.

Maybe you can take some ideas from the vampire onslaught event deck released by wizards (http://archive.wizards.com/Magic/magazine/article.aspx?x=mtg/daily/arcana/766) or from a revision I did for myself (http://www.mtgvault.com/muktol/decks/vampire-onslaught-revised/)

Greetings
Muktol

*like*
Some suggestions, based on my own monoR Krenko commander deck (http://www.mtgvault.com/muktol/decks/edh-krenko-mob-boss/)
Untap artifacts: Illusionist's Bracers, Magewright's Stone, Thousand-Year Elixir
Mass-pump artifacts: Konda's Banner
Creatures: Bloodmark Mentor, Caterwauling Boggart, Goblin Assassin
Instants/ Sorcerys: Massive Raid, Mob Justice, Goblin War Strike

*like*
Some suggestions, based on my own monoR Krenko commander deck (http://www.mtgvault.com/muktol/decks/edh-krenko-mob-boss/)
Bloodmark Mentor, Arms Dealer, Furystoke Giant
Magewright's Stone, Illusionist's Bracers, Thousand-Year Elixir, Konda's Banner
Shared Animosity

I would remove some of the weak creatures (e.g. "Skirk Marauder" or "Goblin Balloon Brigade") and adds some more mass-pump (e.g. "Coat of Arms", "Konda's Banner") or artifacts with tap/untap or copy abilitys (e.g. "Magewright's Stone", "Illusionist's Bracers")
Also some protection like hexproof for Krenko can be useful. From my experience, if your opponent can't get rid of Krenko, or has a lot of mass-removal, than its game over for him.

Greetings
Muktol