Hi Ralph!
Let's see what we can do for you!
Yes, sounds like 2 separate issues so let's tackle them one by one. First off, the coin/credit issue, that sounds like a button maybe not working properly is all. Can you lift the door/lid and take a look at the button assembly for the Credit button? Sounds like its just not making contact or is maybe not plugged in. Get under there and compare it to the Spin button, or Bet 1 button, whatever button you know is working fine. Look for loose, unattached wires, melted stuff, etc.
Bill Validator Issue - Sounds like it is either Disable in the menu or the software is not compatible with your machine. No problem on either note, but you we would refer to know what SP chip you are running on your MPU board. Pull the MPU (the big silver tray with the black knob on the outside), which holds the MPU board. On the MPU board, you will see some black 1/2"x1.5" EPROMs. Hopefully, they are labeled, and we are looking for the one that starts with SP, like SP731, SP1271, etc. If you can get us that info we can help more with your issue.
If you have any problems, just post back, were here pretty much 24/7!