Yes, you can.
The iMac does not run off a battery nor does it contain a battery. It runs strictly off AC power and must be plugged in.
Yes, if you have the Macintosh version. The Windows version will not run on an iMac.
I am almost positive you need a dual monitor card to run tow monitors off the same computer, because if you don't have a monitor card then you wouldn't be able to run the monitors at all
to be honest, you are far better off buying a new computer monitor. why not go for an LCD Monitor. its cheaper to run...and pays for its self in the long run.
You can install Windows onto your iMac and boot into the Windows OS using BootCamp. Though if you wish to run Windows while still working/using your Mac OS, you should refer to Parallels or VMFusion. These programs enable you to open a virtual desktop running Windows XP/Vista in a separate window.
Im thinking of buying a imac g5 but I don't know if I can run Minecraft on it
No it will not run on a Mac.
No it will not, But it may overheat and corrupt your RAM which will make your server slow.
An iMac G5 can only run Mac OS X 10.5 (Leopard) it cannot run 10.6 (Snow Leopard) or 10.7 (Lion). So the answer must be 'No'.
If you are asking about cheats for games that run on iMac, you should try using a Google search: "Cheats for on mac"
There is no Mac version of Maple Story but if you have a recent iMac with an Intel processor than you can run Windows on your iMac and play the Windows version of Maple Story - see related link below for details.
CrossOver requires a Mac with an Intel Core Duo processor to replicate a Windows type computer. It will not work on a G5 iMac.