1. There is no spoon.... ehhr "DR tanking". DR is what you add to other forms to lessen the strain on the healer.
So I can "hate" tank even w/o using a shield to begin with?
2. You dont need to be one of the AC-PrEs to "tank".
That's good to know ^^
3. No. Not by faaaaaaaaaaaar. - If you want to keep aggro, there are only 2 ways:
Intimidate high enough, or
Hate generation high enough.
W/c is more easier to accomplish then? I am leaning to get both
4. The more, the better, but there is no minimum needed.
yey! XD
5. (The question not asked, but most important

) You should aim to reach
at least 600 HP before shorttime buffs (madstone, bursts, etc...) if you want to be eligible as a maintank. And no, this is not unbelievable high, my Rogue reaches that. And if he can, so can your Fighter/Barbarian/Paladin.
The reason I never asked that is because its mandatory even for non-tanks to have big hp pools 