What are people doing for sub installs?

Can we use mixed wired lead and RCA outputs?

EX:

Door speakers: wired leads

Sub: RCA preout

Does the following settings have this effect?

Rear speaker: Full

Preout: Subwoofer

With those above settings, can I configure the High Pass ONLY on the door speakers (F+R wired leads) and the Sub Frequency ONLY on the RCA preout?

I'm not sure what you're trying to do. If you're adding a sub just use the sub preouts. High pass preouts are just if you're using an amp for the highs.

Im assuming your using either the 01 or 02 variant since it only has one set of pre outs... if your into bass use the pre outs for the sub if ur into all roubd goid sound use the pre outs for the rears and use a line in covert for ur sub