I know this has probably come up before but I just want a quick answer 
I have a SONY HDTV and am considering the purchase of an iMac 21.5"
Can you dual screen output the iMac to the TV via HDMI (or any other way) ? Or can you only view it on the iMac screen? I know that you can output to an Apple Thunderbolt Monitor, but I don't want to pay another £800! Can you do it through a HDMI cable? If not, and there are no HDMI ports on the iMac, then can you get device/cable that switched thunderbolt to HDMI?
Another thing
Can you airplay and mirror your iMac to an Apple TV. I do this with my iPhone and iPad, but am interested if you can do this with a Mac?
Thanks very much!
Cam

I have a SONY HDTV and am considering the purchase of an iMac 21.5"
Can you dual screen output the iMac to the TV via HDMI (or any other way) ? Or can you only view it on the iMac screen? I know that you can output to an Apple Thunderbolt Monitor, but I don't want to pay another £800! Can you do it through a HDMI cable? If not, and there are no HDMI ports on the iMac, then can you get device/cable that switched thunderbolt to HDMI?
Another thing
Can you airplay and mirror your iMac to an Apple TV. I do this with my iPhone and iPad, but am interested if you can do this with a Mac?
Thanks very much!
Cam