| I wouldn't worry too much about the soundpost dropping if you move the bridge carefully and don't take all the pressure off the bridge. I've moved bridges, removed bridges, taken all the strings off at once (all the things you're not supposed to do, but I was young!) and I never had the sound post drop in 20 years. Some basses are shipped from the manufacturer with the bridge not fitted, but the soundpost is still in place... although in those cases it's often too tight to begine with!
Lay the bass on its back (on a bed is a good idea) and loosen the strings enough so that you can ease the bridge over without destroying the varnish. The feet of the bridge should line up with the two 'nicks' on the inside edge of the ff-holes, and centered on the body. When you're satisfied that the bridge is in the right position and the feet are perfectly flat on the body, bring the strings up to pitch a little at a time, just a couple of turns per string so the pressure is brought up evenly. That should do it!
As for the fingerboard, is the crack actually in the fingerboard, or does it look like the fingerboard is pulling away from the neck? If the latter, you may not need a new fingerboard but you should get the bass to a luthier as soon as you get the chance.
Let us know how you get on!
Cheers,
Tony | 
urgent! Gig in two hours. Need help re-setting bridge. 
