It is best to use a metal gasket that comes with a coating like the original gasket - these require no sealant. If you use a fiber gasket with with sealant, use a minimal amount of sealant - excess sealant can break off after it hardens and get stuck in the small coolant passages in the head.
For draining coolant. I typically drain it directly from the hose on the thermostat when I disconnect it. I use a plastic storage tub underneath the car to catch all of the coolant when it drains.
Many people will also replace the engine mount while they are doing the water pump. It's located in the same area and it is easier to reach all the bolts while the engine mount is removed.