The second battery is for smoother electronic stop/start. The 392 does not have an aux battery since there is no ESS. That is the best way to do a battery delete. :D
I see this from time to time on my TRX infotainment system. It is some garbage that Stellantis likes to install on our systems, I think related to telematics. (My JK doesn't have the fancy radio, etc)
I read a lot of reviews and settled on a GOOLOO GT4000S, it has enough boost power to turn over my TRX when it is dead as a door nail and still has 80% left. Seems to be a quality unit, but it is expensive.
I have the wireless dongle for my Warn and it works very well, however, I always carry my wired controller. I love the wireless for moving logs and obstacles around the propery.
I would not upgrade gears before moving to the D44 in front, it is expensive to regear and you do not want to have to do it twice in the front. I put a prorock 44 in before I regeared. I have a '17 JKU with '37s and 4.88 gears works just fine for me, both wheeling and highway driving.