#2: Gear doesn't need to be compact since the footprint is the same, however smaller gear can give you more space options.
#3: most apartments don't want you to wall mount anything except pictures, so attaching a wall mount to studs is likely a no-no. What most people I've seen do is get a stand that includes a mount. Since I already had my rack, I went with a stand alone mount that fits below and behind the rack.