As far as the internal memory. I am not sure if it's battery or not - I have never heard of anyone having to replace a battery in a 3DO but I could be wrong. I think it's flash based most likely but don't quote me. You should do a search online for the Game Guru disk, it's a pretty neat memory manager utility. If you have the FZ-10 then you don't really need it unless you want to use cheats.
I should find a copy of it, my 3DO is an FZ-1. Now about the Game Guru disc, is it official game disc or something you have to download and burn yourself?
What's up with islands? Get more land.
What's up with deserts? Get less sand.