'Living' Death Knights

[Mortiphobia]

I've heard this term thrown around and I think we have one on CotH. It's not so much the concept that confuses me as what sets them apart from their unliving comrades. Some of my questions may sound silly, but it's simply because I'm a curious fellow and like to have a complete (or as complete as can be) knowledge on things. My questions about living death knights are as follows:

Do they need to eat?
Do they need to sleep?
Can they reproduce?
Given the above question, do they even have sexual desire?
Are they immortal like their undead brethren?
Are their fives senses intact (though perhaps a bit numb)?
Just what bodily functions, if any, do they have (breathing, using the bathroom, etc.)?
Possible to become inebriated?

I'm sure there are many more things I'd be curious about, but these are what I came up with of the top of my head. Perhaps I'm just confused and such a death knight doesn't exist, but I'd think there might be a difference between a 3rd generation DK (ones that actually died) and something like Arthas (never having died, but became corrupted).

So, CotH, care to teach me something? Any kind of feedback is appreciated.