Flexible conduit for cabling is a must and future proofs you for new technologies.
In floor heating underneath solid surface floors isn't a must but is really nice to have if you can afford it.
Also consider a "false wall" if you are going with a projector and screen. I have a projection setup and I had square footage to spare, so I built my projection screen wall out about 30 inches from the foundation wall. This allowed me to hide my speakers and subwoofers behind an accoustically transparent screen.
This guy knows what's up :yes:
Prewire and conduit. Gives you what you need now and the ability to change it in the future.