your Theme looks good. i like the idead of using the rb logo as an hdd indicator. I'm not so good with all these licenses neither, so i don't think i'm can help you with that. But if all the images you have taken are from themes, which were published under a CC or GPL license, i think you can use them if you mention the authors name, without his permission.
PS: As you can now use conditional viewports, i generally think that these album "art not available" images don't have to be there. Instead you could draw a big viewport there, which holds information on the current track (like album artist, album, song, year, rating, size etc.) using the big font.
To your newbie question:
Answer can be found, if you click on "more formatting help" at the bottom of the wiki edit page:
CapitalizedWordsStuckTogether (or WikiWords) will produce a link automatically if preceded by whitespace or parenthesis.
TIP If you want to link to a topic in a different web write Otherweb.TopicName.
HELP The link label excludes the name of the web, e.g. only the topic name is shown. As an exception, the name of the web is shown for the WebHome topic.
It's generally a good idea to use the TWikiVariables %TWIKIWEB% and %MAINWEB% instead of TWiki and Main.
Prevent a Link:
Prevent a WikiWord from being linked by prepending it with an exclamation point.