1) if the S-charger belt breaks..... will the engine still get me home?
Yes, without any problems. It'll just be slow as molasses!
2) Is the auto/transmission good, it doesn't have any leaks or slippage right now?
The 4R100 in the Gen 2 Lightnings are tough cookies. They have the same internals the PSD 4R100's have.
3) Is the ring/pinion harder than usual to change because it has a 4.11 now and I'd Reuther have a higher gear in the low 3's
What makes you think it has 4.11's? If anything it'd be 4.10's (pretty sure someone wouldn't change it to a 4.56) but it wouldn't be 4.11's. Ford doesn't offer a 4.11 gear for the 9.75 rear end. I'm pretty sure there isn't an aftermarket R & P gear available in that size too, but I could be wrong.
I guess I should ask, why do you think the gear has been changed from the OEM 3.55's?