From what I can gather sounds like to need to take a few links out of your chain and stick the snailcams back on. If they dont fit either run them on the outside or just ram em' in.
This
But on the crank problem, just take the crankbolts out and ride it for a little while until they work their way loose. Or just wack em' with a hammer.
You need to hold the grinder at a steeper angle to bite into the rim more, ive used really worn out - near smooth discs in the past and can still get a good grind out of them. You just have to adjust the grinder to the best angle to get it to bite into the rim.
Concentrate on getting those arms and legs bent a bit, youve really got to sit into the bike when you preload. Just stick at it the rear wheel control will come, focus on getting those arms bent.