#1
any one else have this? what could it be? i realized that i could have 5 intonated perfectly, but then i go to intonate the last one and when im done and go back to the whole guitar to do one last check, they're all sharp except for that last string which is intonated.
#2
Got a trem? You need to make sure it's set up properly and that you're intonating and tuning so as not to throw it out of whack.

Otherwise you're intonating and then moving the bridge. No good.
#5
That's a good strategy if the trem is set up properly, but I worry OP is doing something like that, and the trem isn't flush so unblocking it throws everything off again. Or the bridge is pulling up as he tunes the strings up one at a time to intonate.
#6
The strings should be in tune before you begin the intonation process, and the distance the intonation will travel fore and aft shouldn't be much. I block between the sustain block and the body back in the spring cavity. I've rarely had to block to keep the back of the Floyd from dropping, but I'm not above doing that, too. That forces the Floyd to be static and horizontal when intonation is done. After that, there may be some minor tuning and or claw adjustment, but the actual intonation will be spot on once that's completed and the Floyd is horizontal again. At that point if you check a single string and the intonation is off, they're all off the same amount, and adjusting the entire Floyd's orientation is what needs to be done.