Multiple partitions, tho not necessary, are generally a good thing... You want to keep the Workbench partition seperate from your general working partitions. It keeps things running smoothly.
With your setup, I would divide it up like this:
100MB Workbench: (for Workbench and such)
300MB Games: (for your games)
300MB Applications: (for non-games)
~300MB Files: (remaining room used to store archives and other junk)
This gives you plenty of room for add-ons to workbench... Ample space for games... Room for Apps (since if you stick around here, you'll end up doing more with that SWEEEEET li'l Miggy than just games)... And of course room to store downloaded archives and files.
As for auto starting Degrader, you can try putting it in S:user-startup (aka Workbench:S/user-startup)... Failing that you can also try it at the end of S:startup-sequence. -- (I've never used Degrader, so someone correct me if I'm mistaken here)
Enjoy!
Edit: Another (MAJOR) advantage of seperate partitions is you can quickformat a partition if for some reason things get out of hand, without destroying everything on the system.
