No, the iMac does not come preloaded with Office. You can however get a great free office program called Open Office or Libre Office.
Not unless you want to use the software. In that case you will need Microsoft Office 2011 for Mac which you will have to purchase. You can also install the free alternative Open Office for Mac.
There are a number of different types of software that advertising agencies used. Often the business staff will use Microsoft Office whilst the creative staff will use iMac compatible software.
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 not without other software.
Microsoft's PowerPoint (See links below) is part of their Office software suite. It is installed with the standard installer - double click the installer and follow the prompts.
You can if it is compatible. It will tell you on the package the software came in.
I not sure...but recently he uses his iMac to film stuff
No. The System Restore discs for a new iMac are specific to that model only.
A video can be recorded with an iMac's iSight webcam using software such as iMovie, PhotoBooth or QuickTime X all of which can be found in the iMac's Applications folder.