1.) That is a great motor.
2.) The mount will work just fine, its what i use with no problems.
3.) Yes, all the traxxas stock parts bolt right up.
4.)20% will be fine, I run 30% in mine.
5.) I would run an OS#8 but try and see.
6.) With this motor you will want to run 36/17 to help calm down the wheelies, plus the picco has no problem pulling this combo.
7.) Yes, you can use the stock neck with a MS air filrer, reguires a little modding. I run a HPI Savage air filter on mine with no modding at all.
http://www2.towerhobbies.com/cgi-bin...?&I=LXJSS8&P=7