If that BB in the pics came with your Shimano Cranks its likely the correct length for the cranks. Like Zorro said, it should be a 68mm Shell on the frame.
If you want to shim the FD I'd recommend a brass bushing, you can get them in nearly any combination of Inside and Outside diameters at a hardware store. You could also just get an FD with the right clamp size, its a double crankset with a not-too-big jump between the chainrings so just about any FD would work.
The crankset thats on there isn't junk either, its a pretty decent one made by SR. Honestly if it were mine I'd probably opt for the original cranks over the shimano ones but thats just personal aesthetic preference.
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--Don't Panic.