Look at this to see what is stored in PRAM. Not replacing the PRAM battery in desktops, and not keeping the backup battery in portables charged, is inconvenient at least and terminal at most, and a false economy of effort and money.
There are primary, one use non-rechargeable, and secondary rechargeable batteries. There are lithium cells in both categories. Despite the appearance of USD0.01 primary lithium half-AA 3.6-V cells in eBay sales, there is more reason to applaud the recycling intention behind them than the utility of the batteries. New lithium primary cells are cheap-as-chips (about USD4) from eBay sellers such as ronaldo101, and have a life of 3-7 years, depending as the Mac is always powered from the mains or not.
The IIvx isn't one of Apple's better moments in computing history. I swapped in a Q700 motherboard into mine, but a Q650 board would be a better choice if you can find one. The IIvx is just snail slow compared to a Quadra. I'd upgrade that sucker as soon as you can.