Welcome back! You should have a peek into the computer and see what kind of accelerator and its speed is in the Fast Slot. Probably a GVP 030 combo card would be my guess. NIC cards are available and pop up on eBay once in a while. For a list of various peripherals, the BBOAH is a great place to start:
http://www.amiga-hardware.comDoes your systems have a hard drive? If its got an 030 and a hard drive, check around the net for something called WHDLoad.
Unix is available also for the Amiga - but might be a pain to install and probably not worth putzing around with unless you're really into that sort of thing.
Do you know what version of AmigaOS you're running by chance? 1.3, 2.1 and 3.1 are typical in old A2000's systems. If all you want to do is play games off of floppy, 1.3 will be good enough. 2.1 is pretty much a waste of time but you can do lots with 3.1. Upgrading the OS on an old Amiga would probably be the first thing I'd tackle if you're wanting to do more than just play games...
(forgot about the battery, great advice Scuzzb494!!)
