Q: I was told by the salesperson that you can use your TV as a monitor for your imac is that correct?

Potentially, yes. The newest versions of OS X that comes with Macs have a feature called AirPlay Mirroring. However, it will also require an Apple TV as well to work.

I have asked the moderators to move this thread to the iMac discussion area... it has nothing to do with AirPort.

You can connect your iMac directly via cable to your TV or use Apple TV and AirPlay as mentioned above.

Yes. I use a TV to extend my desktop all the time. You can also mirror the screen of your iMac to your TV. As Tesserax pointed out you'll need an Apple TV. However unless your TV is really nice (mine is not) you will not find a better picture quality using your TV as a monitor.

How To Hook A Imac To Tv via HDMI