The change that you're proposing will only result in a gear that's about 1 1/2 gear/inches easier. That's not very much difference so, if it was my bike, I'd say it wasn't worth the effort.

Accurate answers to your other questions depend on missing information. Bottom bracket type and size, for example, depend on what the replacement crankset is. Necessary tools depend on exactly what you are doing and, to a degree, what your present equipment is.