if you buy almost any modern mtb crankset with external BB, you'll get the BB with the crankset. You'll need the proper tool to install the external bearing cups (all the common brands use a universal design. I have the park one, and it's been a good tool) plus you'll need a tool to remove the old BB. I wouldn't waste time on an "upgrade" that's using square taper or octalink/isis. FWIW, most of 'em will say they fit 68mm/73mm BB shells. You've got a 68mm, which is good news because you'll be using spacers to fine-tune your chainline. You can get raceface evolves really cheap, but the BB's tend to be garbage. Lucky thing is, the shimano external BBs fit the RF cranks. You can also get phil or king cups down the line if you enjoy spendiing money. Truvativ makes cranks for you. While they use the same install tool, the crank's spindle will not fit shimano BB's and other shimano-compat BBs. I personally didn't much like my truvativ external-bearing crank, because the bolt is on the non-drive side, and it will work itself out if you don't pay attention to it, which will allow the crankarm to work itself off, and dirt will foul the bearings. The RF puts the bolt on the driveside, which doesn't self-loosen like the leftside will. Shimano puts the fasteners on the left side, but it uses a wierd plastic jimpson and pinch bolts. I have a shimano LX crank from the first year that shimano LX went external, and they've been awesome. A $40 BB does the trick when the bearings get sloppy, and you can get some decent time out of the bearings depending on how you ride. Still, I grabbed a raceface evolve because it was ungodly cheap, and I'll just put some XT cups in when the RF bearings are shot. A friend has been riding the same evolve cranks forever with no real problems. His BB has even held up all season.
HTH. sorry for the long and rambling post.
oh, the other stuff:
-the hanger and tube is easily replaced. The FD may be repairable. If not, get whatever suits your budget and fits. FDs don't work as hard as RDs.
-Um, get a new cable for the computer, or maybe don't have a computer, if you're short on cash.
-all the rings/crankarms will come with the crankset. I'm surprised your chain wasn't damaged.
-start saving for a new wheelset.