Intro and beginner questions

Hello, everyone,

New member here installing a system into my 1985 VW Westy.

I just finished building a sub enclosure and buying an amp but I have a couple of questions before I move forward. My head unit (Kenwood KDC-BT372U) has 3 sets of preamp outs - front, rear, and sub. If I install a multi-channel amp for the front and rear speakers and a separate mono amp for the sub (using the processor to tune, then sending preamp output to the sub amp), would I use only the front pre-outs on the h/u? Or fronts and sub pre-outs and combine them in the DSP? My head unit has bass controls (bass level and bass boost, iirc), but would i need these if I'm using a DSP?

Related question - if I end up utilizing the bass controls on my h/u, would I need to use the amp's remote?

Thanks!
Will

My van:
Attachment 11453
Sub enclosure:
Attachment 11454
Attachment 11456