4) Kernels sound better after they've been worn in a bit. Don't expect your
newly built 2.4 kernel to have that warm sound until you've run with it
for a few weeks, but for a really classy sound here's a trick: compile the
kernel and then put it somewhere safe (ext2 partition, obviously) to mellow
for a month and then boot into it at the last minute before you start
recording an important session. Your clients will thank you.
You generally don't develop for a single distro: you develop for linux. Which then works on every distro. If you're optimistic enough you could even try to make it work for every *nix, but whatever.
The only reason steam is made specifically for ubuntu is because it uses apt-get to actually get steam. If valve put more effort into making it like every other linux application nobody on any distro would have trouble running it.
Ubuntu is less strict on the non-free thing. Either way it doesn't really matter since you can use PPAs from ubuntu on debian and vice versa. Obviously the same goes for .deb
I think ubuntu LTS gets packages from wheezy and normal ubuntu from sid.