Don't overlook the possibility that the problem is in the pedals. In my experience "crunchy" as you put it most often comes from the pedals as do squeeks.

If you have to change the BB, it is an easy thing - especially if you are replacing a cartridge bearing. The question is whether or not you have the correct tools for the job. If you do, it is as easy as putting a hot dog into a bun. If you don't have the right tools, it will be like putting a bun inside of a hot dog.