Replacing Themostat and Thermostat Housing

Looks like I need to replace the Thermostat housing on my 2001. I have a small leak at the base of the housing so I'm thinking the rubber gasket has failed. I picked up a replacement thermostate with a new housing today at Napa. Need to know a couple of things:

1) Proper procedure to drain the fluid so it doesn't get into my alternator.

2) Proper procedure to refill the system after I replace the parts.


Thanks in advance.

Bryan