Hey, some thoughts on the electrical:
- Consider how many circuits you’ll need.
- Stereo
- Lights
- PC ?
- What about heating and cooling?
You may be better off running a 60A circuit to a sub panel in the building and will perform better than a single 10/2 gauge cable. If you install a sub-panel, install a surge protector there too, especially in lightning/storm prone areas. Put one in your main panel as well.
Budget for room treatment. You'll need a mix of absorption and dispersion, including the ceiling. The more controlled dispersion your speakers are the less important this is but still. Drywall over anything isn't great alone.