1. I actually got to chill with Michael's
Guitar Tech once and he told me that Michael is one of the few people that likes the tone he gets from the TZ in the neck. (According to him, M.R.'s almost always on it). On one of his other guitars(the purple ESP I believe) he's got two EMG 81's in it.
Note: M.R.'s new Caparison Dellinger II guitar actually has the X2N/TZ combo again. It's actually not that bad of a
neck pickup, but will require the use of an EQ to get rid of the muddyness(I built a passive Low-Cut/Mid-Cut circuit to get rid of the muddy low end).
2. As long as the nut holds, it shouldn't be a problem. If you can move the nut around without the other screw, that's another story.
Hope that helps.