This sounds like a quick way to burn out your video card and all you'll get out of it is $5-10, if you're lucky.
Stick to gaming and let the professionals mine bitcoins.
1)Gamers usually ARE the professionals
2)No, the card won't burn out. Guess what, it's MADE to work. You buy it to USE IT! (of course you have to check temperatures)
Bad idea, if I mine my computer is very slow, I have to stop my other programs.
I have no problems, i always mine while i use my pc. Of course i stop mining when i play. Just disable gpu for the browser and flash