ok, so with that serial, it's definitely a '99. have a look:
http://www.prsguitars.com/csc/year.html
scroll down to 'set-neck serial numbers'.
the serial would also seem to suggest it's not a CE, as they have a different serial numbering system. (scroll down a little further.) a CE would be prefixed by a '7' or the letters 'CE'.
without being able to look closer, my guess is that what you have there could very well be a custom 22 (i prefer the set-neck to the bolt-on anyway). i have a 2002 custom 22 and it looks very similar. i'm sure someone with better knowledge of these guitars could offer you a better guess.
it looks like a nice top - probably maple with a tobacco burst or something similar. but i'd be careful of all the dust, especially if, as you say, it's gotten into the electronics. you may have to replace / have a lot of work done from pots to pups, not to mention the potential damage even fine dust can do to the finish. be careful wiping the guitar tonight if it's not necessary.
good luck
dh