also, with the boosted jazz mode, are you saying to put the pickup select knob all the away down, and then put it in power tap mode?
Nope, just to have both pickups on and have it in power tap mode.
Linnin is clearer on the Rumbles gain structure and OD then I so his post is also helpful (though he confused my non-boosted/boosted part to be about the amp I meant the bass).
On the pedal front I've got no clue what would be best tbh. There's such a wide variety of pedals and ways they can shape your tone and I've got no clue what he's using.