Multiple Tank Syndrome
Lens Buying Addiction
Camera Buying Addiction
I suffer from all three.
MTS Somewhere near 30 tanks to be setup in the new fish room.
LBA Too many to count and more money than I care to add up.
CBA Nine or 10 camera bodies. I use all of them at one time or another.
As for white balance. Set it to auto. It'll get you close enough in most cases depending on the camera. Mine does it great about 98% of the time. Since I shoot raw+ it's not really a problem.
As for ISO. You are correct that it is the sensitivity of the sensor but what it allows you to do is either stop the lens down, increase shutter speed or both. Higher ISO's will allow you to shoot in a darker environment and get a correct exposure. It won't just make the pictures brighter. Opening the lens or slowing the shutter will also make them brighter. Or overexposed. Your choice.
Generally you will find my camera set to 400. And if I am just walking with it I will set it to full auto instead of manual. Why? Because there are times when you're walking/driving along and a shot just hits you. Keeping it full auto will allow you to at least get something.