If I want to install and use a different desktop environment than came with my distro, what (if any) problems can I expect to encounter?
I currently use Debian with GNOME and I want an optimised system for music production and graphic design. As far as I can tell, the two main options I have are to make some tweaks to my current system's configuration (rt kernel, swap use, cpu behaviour and others) or to switch to a dedicated media distro which is configured already. The creative distros that I like the look of don't use GNOME though.
Which option will be easiest for me?
I'm not knowledgeable about kernel tweaks, but switching DEs is very easy on Debian and should not cause any problems. Just install the desktop metapackage (e.g., "task-kde-desktop") and you'll be able to choose it from the login screen.