Hey Sam - agree wholeheartedly with DB here - you're not getting much for the screws to hold onto on the back of the body if you were looking to bolt on. You could possibly mod yourself, but it's way out of my league in how to do it - that and you'd have to really understand your stuff to do so (remember the amount of tension in bass strings is HUGE). Set necks can be replaced - use the right glue and you can generally get them off with not too much hassle (i.e., some come off with steaming / heat). If the worst was to happen (i.e., you drop it and crack the neck), drop a line on the forum and there should be some help here - the plan is that forum's here for the life of the guitar, not just during the build .

As for colour - my approach is driven by the guitar - see what the grain, etc is like and then drift with that.