Yes! A lot of people do this!
I personally don't have experience doing it, but it's becoming quite common.
As for resolution, of course higher numbers are bigger... you'll find 1920X1080 to probably be the most common... at least with anything bigger than say 25".
You might also want to make sure the model you want to purchase has a "PC Mode" or "One-to-One Pixel" mode...
One problem with using a TV as a monitor is the TV will sometimes add a slight amount of latency between the video card and the screen (to process the image) and this can cause some issues with gaming. Some people notice it and some don't. Some TV's are better than others.. just make sure you do your research.