Will answer what I can.
For the Genesis, I have no idea.
As for the bearings, I would get them repacked and just have the piece of mind they are done now. I did it for mine. I twas less than a year old, but the manufacturer puts so little grease in there, get them done. You will be good for 5K miles or more then.
I have a 2013 chevy 3/4 ton with the integrated brake controller. For my 25 foot cruise like, I have my gain set at 3.0.
What I did was get on a BIG hill. then adjust the gain so I could hold the trailer.
That came out at 3.0 on the controller
2015 32 Foot Rockwood 8289WS 5th Wheel
2013 Chevy 3/4 Ton TV