Doing to be doing a new build for me:

-Heavy Armor (Ebony or Daedric)

-Conjuration

-One-Handed (or Two-Handed?)

-Destruction

What's a fast way to get Ebony armor?

Know any good helmets to match Ebony Armor, other than Ebony Helmet?

Any cool hoods in the game I can use instead of a helmet?

Do you think one-handed plus magic in off-handed is better, or two-handed and switch to magic is better?

Really the fastest way to get ebony armor is just raise your smithing skill. By the time you're able to do Boethia's daedric quest, your smithing could be well above what you need to unlock it in the smithing tree. For a deathknight I'd recommend two handed, like a battle axe just fits that character perfectly. Thats your main way of dealing damage.

As far as helmets, the last few characters I've done have gone helmetless as I like the way they look without them. I will say however, I had a mage once that used a full set of daedric armor with the college hood and that looked pretty bad ass.

I would definately do the two handed then switch to magic if needed. Also, the ritual stone is your friend with that build.

D_D answered it pretty well.

Just raise your Smithing as there is no other way to get it.

Warrior Stone, Lover's Stone, Lover's Comfort. Make Dwarven Bows and jewelry.

Warcraft Deathknight? I'd say Conjuration, Restoration and Enchanting, not Destruction.

http://theskyrimblog.ning.com/group/character-building/forum/topics/character-build-dark-knight

For helmets that match Ebony armour, the Masque of Clavicus Vile uses the same colour scheme so it fits in with Ebony armour. Whether you think it looks good with it is up to you.