1. You could try taking the baseplate off & turning it over (so the rubber is inside the case). But if you get some decent heavy duty Velcro & wipe the rubber with some meths, it should stick ok.
2. As long as your 9v PSU supplies enough amps & your polarities are ok, then fine.
3. There isn't a "best way" as such, it's down to what YOU like. Experimentation is the key (& 1/2 the fun).
Other advice? Learn to spell Board & listen to classical music.
Recommended pedals? If you don't know what you're gonna use, then plug into your computer or get a multi fx. No point buying a type of pedal someone else suggests as you might have no use for it.
I'd say get a Moog Bass Murf, but you might find it as useful as a brick. I on the other hand, love what it does.