Colin, you're in for a great experience! The dub stage is my favorite part of the process because it's where everything comes together, collaboration takes place and the final vision is achieved. The flip side: Personalities (read: egos), long hours, junk food, time away from your family and many dBs hammering away at your skull. But those are not all necessarily bad things… :)
Some notes on workflow from my experiences:
MACHINE ROOM: The backroom person is your friend! He/she is your point person, making sure that all the correct sync/frame rate/bussing issues are taken care of, coordinating any plug-in needs and version snafus, directing you to servers and informing you of how the stage operates.
WHERE YOU WILL LIVE: Depending on your job title, you will find yourself hanging out on one side of the console most of the time, either the Dialog/Music side or the FX side. Or, if you're supervising, you'll be in the middle.
TRACK DELIVERY: This varies widely, with some crews sending traditional mono/stereo tracks to the stage for predubbing, and others delivering virtual 5.1 premixes with live plug-in automation running. It is CRITICAL to discuss this with your mixers, engineers & post-production supervisor ahead of time so there are no surprises. If you go the virtual route you have to be sure that the stage has all the same plug-ins that you have!
CUE SHEETS: Your mixers will be expecting these. Make sure you know how to generate them from your session and double-check them before you arrive for legibility or potential mixing problems (ie. same material is not on the same track, not enough room between events for the mixer to make his moves, etc.) Often you don't see that kind of problem on the editing screen but it becomes evident on paper.
STEMS: Traditional configuration is DIA stem (LCR or 5.0), FX stem (5.1), BG stem (5.0 or 5.1), FOLEY stem (LCR), MX stem (5.1). Channel assignments depend on the complexity of the project, ie. 5.0 DIA stem vs. LCR DIA stem. Also, some of the busier shows will have an extra stem for a particular item in the movie, say a MONSTER 5.1 stem or a WATER 5.1 stem.
AVID/PICTURE CREW: I have yet to work on a film where the picture crew actually had the Avid on stage. They are often nearby (sometimes across town) but very seldom are they set up on stage. Projecting the image is normally done through a projector room and not off the Avid.