When I was having my house built, I ran Cat5 cable, extra TV outlets and put rockwool in all interior walls between bedrooms and other rooms in the house.
You may recognize Rockwool as the brand name of the stuff that is used in Gas Log fireplaces to look like glowing embers.
This stuff is a LOT heavier than fiberglass, and VERY fire-resistant.
To this day the only sounds coming into the bedrooms are from around/through the doors themselves.
I would put a few flourescent fixtures in the garage. My house is on a basement with about 1.5 feet of room between the garage floor and where the main level is, so I was able to run 220 and 120 lines easily to my garage AFTER the house was built.
If I were you I would do it BEFORE, but then I don't know what your configuration is.