Just found out I'm getting one as a gift, and it's in the mail. While I've got 4 days till it gets here, when it comes outta the box, what should I be looking to do with all those wonderful little knobs and buttons?

Also, can I use it to bypass the crappy preamp section of my Bheringer head by plugging my bass into the Sansamp and running it's output in to the effects return jack on my head?
Traben Array
2x Tech21 Sansamp RBI Bass preamps
450w Power Amp
2x Gallien-Krueger 410
Handmade nylon-string classical guitar
Jackson DXMG Dinky
Line 6 Spider 2 250w combo
Various Lee Oskar and Honer harmonicas
Yamaha YPT-310
Yes you can use it to bypass the crappy preamp section of your head. I have the pedal version of the RBI and I bypass my amps preamp asweel. Just stick into the return jack. As for settings, it all depends on what you want. My tone is fairly growly with quite abit of distortion. Mine is like; level - whatever I need it for as its only volume, blend - full, treble - 11:00, bass - 12:00, drive 1:00, presence - full. Now I know you have a mid knob aswell, mine doesn't but thats why I use a Boss EQ pedal. You may want to put in alittle mid as you may be left out of the mix. Other than that just mess around, you will find lots of neat tones with that thing and I'm sure the preamp will come with an instruction manual containing some settings of its own as my pedal did.
EBMM Bongo HS 4
EBMM Sting Ray 5
Eden D410T
Tech 21 Sansamp RBI
Tech 21 Sansamp RPM
Art 341 Dual Channel EQ
QSC GX5 Power Amp