mtmc:
The 'official' way of doing it is to drop the pan and use a big catch pot under the pan. I forked out for a new FRPP drain pan that has a drain plug (hey, I can't take all my riches with me, can I?) but there are "add-a-plug" kits available or you can weld in a bung for a plug if you are handy with a welding machine.
There is no secret to draining the transmission. ATF will hide in a few spots but you can't really get it out until you start taking things apart. Let it drain for a long time is, of course, one piece of advice. The valvebody will hold up a little fluid (0.5 to 0.75 pints) but that can't be avoided, imho, so just be prepared for it.
I have not rebuilt an automatic so I am far from being an authority on the subject. Check out "Transmissions 101" by Jerry Wroblewski (former Ford Transmission Engineer) in the Tech Articles/Transmissions section of TCCoA.com. Excellent series of articles, including several about building a bulletproof 4R70W.
HTH,
Chris