70 FAHRENHEIT is super cool, your PC must be in a fridge.

70 CELSIUS is a good temp, especially with an OC.
70%

who knows
Get GPU-Z to read your GPU's temperature sensors.
Its not recommended to mine 24/7 with fan speed at 90%+. Try to keep below 80%. The GPU fan may fail much sooner if you don't.
CGMINER is good for setting fans speeds, clock speeds, etc. It is command line app, you'll need to read up on it.
My temps are around 60°C to 71°C with fan speed at 80%. So I guess the card and fan would be ok then running 24/7
ATI Sapphire Radeon 7950 OC Edition.