As I know there are a fair amount of electrical guys on here:

Just went through 4 hours of load shedding. Now I want to connect an inverter to my car battery - just to run my 32inch LED TV and DSTV player.

Could you maybe tell me VERY ROUGHLY

1) What sort of inverter I would need - thinking a 500W modified sine should be ok?
2) How many hours can be safely taken out of the battery (standard 12v car battery) - I do not want to kill the battery!