One most important thing that you can do for yourself and your Gigabeat after installing Rockbox, is to take the time to read the manual. (Linked on the left side of this page.)
Many of your questions will be answered there.
1) Album Art requires an unofficial build. An unofficial build is just a build with patches applied to enable a certain feature. Creating an environment for applying patches and compiling your own build can be a long process to setup. Once you're setup though, subsequent patching is really easy. If the task is daunting, you can grab someone else's build from the "unsupported builds" thread at the bottom of the forum.
Note: Unsupport builds are, just that, not supported ... Except in the unsupported builds thread of the forum. If you have a problem, you have to load an official build to see if the problems are specific to the unsupported build or the official one.
2)What you use to "rip" cds is mostly a personal choice. If you are using Windows/Windows Media Player, make sure you set it to rip your cds into the mp3 format. This is a crucial step.
I personally use Exact Audio Copy (EAC) found at the link:
http://www.exactaudiocopy.de/3)Fonts have to go in the /.rockbox/Fonts folder. Then you can just go through the menu -> Settings -> General Settings -> Display -> Browse Fonts to try the different fonts available. Search the forum/wiki when you are ready to convert your own fonts for use with Rockbox. Again, the manual explains this further.
4)Manual has a great explanation of this and can be lengthy to go into here. So lastly the manual is our friend.
Good luck.