Buy two long 2' socket extensions, and a wobble-head socket sized to the bellhousing bolts. It makes removal and installation much easier whether you're using an air ratchet or hand tools.
Never, ever use the bellhousing bolts to pull the trans onto the engine...the trans housing is aluminum and you will break it. If it won't push flat against the engine by hand, it's not aligned right.
Do what the other guy said regarding the torque converter. Pour fluid into it until it's full, then slide it onto the trans input shaft while gently rotating. Keep pushing in and rotating to ensure it is fully seated...it's possible to mount the trans w/ the converter not engaged to the pump, and you'll destroy your new trans.
Get a flywheel turner tool, only costs $15 or so at NAPA and you'll be glad you have it when removing and installing the torque converter bolts.
Use an accurate torque wrench when installing the bellhousing bolts and torque converter bolts. I like Loctite thread locker (blue for bellhousing, red for converter).
Find the torque specs for the bellhousing and converter bolts. They're in the Haynes/Chilton manuals. Mine's in the garage and it's freezing out there. Probably posted here somewhere.
Brake parts cleaner is great for cleaning bolt threads, grab a can while you're picking up the extensions/socket/Loctite/etc.