Answers to your questions.
1) There is only 1 motherboard IDE connector (PRIMARY port). You can connect up to two devices (MASTER and SLAVE). I'd advise on getting a bigger hard drive (for the MASTER) and a CD-RW (for the SLAVE). This way you can run OS3.9 and also do backups of your system through the CD-RW drive.
2) The motherboard memory slots can be used with up to 16MB of memory. You can either use 4x4MBs or 2x8MBs, although I'm not sure how to set jumpers in the case of 2x8MBs. Maybe there's an option to even use 1MB simms for a total of 2 or 4MB of RAM, but who needs THAT little memory anyway? :-)
3) Remove the battery by desoldering the legs from the other side of the motherboard. Of course for that you'd need to get it out of the A4000D case first. Once you unscrew it/get it out, use compressed air spray to get off the large chunks of dirt first, then use a PCB cleaning spray and spray the dirty/dusty motherboard good. Afterwards, leave the motherboard to dry for 30 minutes or so. Once it's dry, spray it with compressed air again to get off any dust leftovers that the PCB cleanser separated from the "glued to the motherboard" state. :-) If you can, get a direct barrel shaped Ni-mH replacement battery and solder it back in place of the old one. This type doesn't leak when old and you will be good for clock time for probably about next 5 years. ;-)
Hope this helps.
