I went ahead and called the local dealer. They were more than nice. Said pulling the drain plug can be a job trying to reinstall since it is a little difficult to access. Advised since I am going to change the t-stat and flush to do the following:

Drain the radiator and remove the stat.

Replace the housing without replacing the stat.

Detach the heater hose coming off the rear drivers side of the engine and flush from there.

Also said I could go back the other way and flush the heater core.

I am scared. Any comments?