A while ago I found a slightly newer G3 imac. I'll impart what I learned from it.
If you have to open it up use a pillow, its own weight on hardwood floor can damage it (learned that the hard way I think I have some minor cracks in mine)
It will always make a *bong* sound...unless you keep some head phones plugged in. Comes in handy if somebody is napping in the room.
It doesn't use CR2032 button cells, it uses these half AA's that went into old cameras. If it forgets the date you'll need one of those.
Mine is 600MHz and I upgraded it to 1 GB of RAM and it still could barely handle OSX and Linux, stick to OS 9.2.2 or under.
The hard disk is a regular PATA one it can be upgraded to something faster and higher capacity, but can only use 120GB or so due to some limitation.
It gets hot....supposedly Steve really hated fans. Seriously a future archeologist could mistake it for a space heater
If you want to browse the web you can use Classilla, you can find all the software you need at macintosh garden.
I was confronted with file formats that I had never heard of. ".sit" and others, Aladdin 'stuffit' can unstuff them.
I don't know about yours, but mine has a port hidden in the back that you can plug a monitor into, but it won't give you a cool two monitor set up it only does screen mirroring.
Anyway, I agree the way to close programs is weird, I agree, I had trouble with that too. One really cool thing with the iMac is that installing games is a hell of a lot easier than on old PCs, you just drag and drop and it works.