2. +12 or (+15 stam gems if you're rich), in every slot
3. I used to use the Warlord for trash and threat fights and the Glory for mitigation fights but I've since just started wearing the glory full time. The only reason I keep the warlord around now is for MT' ing kael.
I have both these, and the Badge Chestpiece. I gemmed the CotW with straight +stam/+150 enchant for a max eff. HP piece, the GotD with +15 defense for my avoidance set, and the badge piece with +stam/+150 for my trash/threat set.
As a raiding OT, I'm in my threat set in hyjal waves, the rest of the time in my avoidance set. When tanking the second or third DPS targets in trash pulls, a threat set is completely unnecessary to hold aggro, so I go with avoidance just to make things that much easier on my healers.
edited to add - before I got the GotD, I used the badge chest for threat/trash and used CotW as my avoidance piece, socketed for Def/dodge and with a +15 defense enchant.