If may be Windows software, or the disc may be empty. It is also possible the disc drive has failed. Try another disc to see if it is actually working.
No, the iMac will not play a Blueray disc.
Yes.
To load a disc in an iMac G4, locate the slot-loading optical drive on the front of the computer. Gently insert the disc into the slot with the label facing up; the drive will automatically pull it in. Ensure that the iMac is powered on, as it will not accept a disc when off. If the disc doesn't load, check for obstructions or ensure the disc is clean and undamaged.
--- Update --- This is not possible; you must use a macbook install disc or a generic install disc.
All the software you need comes preinstalled on an iMac.
The 2011 iMac comes preloaded with the iLife software bundle, which includes GarageBand.
The Apple App store. There is lots of free software there.
The iMac doesn't come with a built-in uninstaller, like the Windows system does. However, you do not need special software to uninstall programs on an iMac. It's as simple as dragging the program over to the trash can and emptying it.
No it will not play a 6" disc. It will play a CD or DVD.
No not without other software.
When you buy a brand new iMac, all you need to do is turn it on and enjoy! It will run the "Setup Assistant," which will prompt you to enter your personalized settings, but after that, you're good to go! Every Mac comes with system restore software on disc (except the new MacBook Airs, which have restore software on a USB flash drive), in case you need to troubleshoot or reinstall later. But it's not necessary to load them to begin with.
You can plug up your 2012 iMac when you are finished using it. Nothing will happen to the iMac. After the iMac is fully charged, make sure to unplug it.