Damiga, your going to have a lot of fun!
Eagle player and Deliplayer are both good for MOD and XM's etc.
You can also convert MP3 files to ADPCM, they sound almost as good, and play just fine.
In terms of getting workbench running sweet (I don't know if a pretty workbench is a priority?)
to make pretty:
NewIcons -They are good looking, but a litlle hungry.
Magicworkbench -OK looking, resource light.
Visual prefs- change the look of windows and gadgets
birdie -pictures in window borders
magic copper - multicoloured copper fade on background (you can overlay pictures on this as well).
ease of use:
ClickToFront- double click on window to bring to front (should be in your tools/commodities folder)
MagicMenu-have all your software on right click menus at the top of the screen
To make it run faster:
FText and FBlit -use your fast ram rather than chip ram for text and graphics ops.
CMQ030 -copymemquick for 030
IconBeFast -speeds up icons
WBCtrl -put icons into fastram
think ACA has a MapRom function?, this will speed up accessing ROM libs.
This thread is (mostly) relevant to you:
http://www.amiga.org/forums/showthread.php?t=50414
