1. Figure out what turbo you have, KKK or Garrett. Adjusting the wastegate is different on them. Or get a boost controller.

2. http://www.superturbodiesel.com/std/thread-ip-full-load-adjustment-procedure-for-the-mw-and-m-pumps-pyrometer-install

3. Dunno, I suppose someone's tried advancing it a few degrees. The angle the injection pump is bolted to the block controls timing, loosen it and it can move.

4. There's no such thing as lean. Although generating more boost than the pump can take advantage of is a waste and just generates heat. I think it's 14psi after modding the pump? The pump can't be modded very far.