Ohhhh, I wish I could help you better, but have you checked aminet, etc. about A500 Zorro adapters, info, etc.? OK, a big box Amiga setup might be easier,etc.... but my first miggy was a 500, so I really would like to see you max that baby out.... no matter what the trouble.....
Hmmm, cv64d's post made me think.... The busboard may or may not need its' own power... but do you have enough power for the beast generally? A High-power PSU should be a priority for a 500*, especially as you expand it.....
About hooking up the 3000 keyboard... have you tried googling 'amiga keyboard pinouts' or tried
http://www.pinouts.ru ?
And, a reset switch........... hmmmmm, I seem to recall that it is possible to add this..... my A1200T Power Tower has a reset button, it doesn't work tho' .... :angry:
Also, here's something....
http://theweeks.org/toms-stuff/top.txt*Some ppl. like A500 PSU's, I know.... I had 2 crap out on me