I have read several places that the best way to extend the life of a
water heater is to regularly drain the water and to check the
sacrificial anode.

Couple of questions:
1. How much water do you need to drain (and how often)? Is it enough
just to drain out a couple of gallons or is it better to drain the
whole thing?

2. I tried checking the sacrificial anode but the hex bolt is stuck in
there real tight. I don't want to break the water or gas fittings
by putting too much force on it and potentially losing my grip on
the water heater body itself. Any suggestions how to loosen up the
hex nut?

Thanks