I third the recommendation to use Hydroton (or whatever replacement your shop has). I've read countless posts from folks trying alternatives in bucket systems. I only know of one person that didn't go back to rock. There is a reason the manufacturers recommend it. It works well.
I know your questions are pretty well answered, but I want to bring up one very important detail that wasn't mentioned...
Yes, you can certainly use the system to drive multiple rooms, but as AK said, keep in mind they will be on the same feeding schedule from the same nutrient mix, so basically they will be the same age and under the same light schedule. The only scenario I can see where this would be useful is when doing experiments testing changes in the environment or something, ie a side by side grow with or without CO2 or something.
That being said, if you want have a single controller/res supply 2 rooms, it can certainly be done. The system won't know the difference, but there is one important thing to keep in mind.
All of the hose must stay on the floor. You cannot have it go up and over anything to get to the other room. So if you want to go through a wall, you will need to cut out the footer to get the hose down to the floor level. That's why most of us that use this type of system have the controllers in the grow room. The reservoir can be outside the room since the water going through those hoses is pumped. The water between the controller and the site buckets are moved by gravity. Hopefully this is clear, but if not, it will become abundantly clear once you start setting up the system.