56: Welcome! Sounds like you're off to a good start!
In regards to your questions:
1) It depends upon how much work you want to do. You can put truck discs on the front without too much modification -- but I can't remember which one fits best. There was a thread not too long ago (within the last year or so) discussing it.
There are also IFS subframes available, but they do require more technical expertise than I currently can provide.
As for the rear, you'll probably have to put a different axle on there. Lots of guys are using camaro axles, but IIRC, my dad's old Camaro had drums all the way around...
2) IIRC, the BBC has the same mount points as a SBC, so you should be fine there. You may have an issue stuffing that behemoth into the engine compartment of that '56, though. You'll also probably want to upgrade your radiator, or put a different fan on it -- or both.
