Looks like most of your questions are answered, but...
Just curious why you don't want to run your generator? I've got a 2015 Charleston 430BH, and with the very low MPG's of the coach, generator on or off really doesn't seem to affect my mileage. The generator draws very little diesel compared to the chassis. So, run it, and enjoy the comfort.
Judging by your questions, it sounds like you're new to this... I was new to this as well 2 years ago... Here's some things I wish I knew from the outset:
One thing I learned the hard way regarding AC units is not to short-cycle your rooftop A/Cs. When you are connecting or disconnecting from shore power to the generator (or briefly shutting off your generator), turn off all your A/C's before interrupting power. Leave the power off for a 5-10 minutes, and then turn it back on once you're transitioned to the next power source. If you leave the A/C's powered when the power is interrupted as the transfer switch transitions from shore to generator (or vice-versa) the A/C breakers will throw and you'll get very hot. This problem gave me fits my first few times out...
I would also highly recommend taking the "Camp Freightliner" class. It was definitely worth the trip to Gaffney, SC. It's much better to know exactly what maintenance you need to perform and when rather than being at the mercy of the wherever you bring it for maintenance.
I don't know if they still use the Magnadyne GPS headunit in your year, but if you have one, you better have a backup system. I've had 3 of the Magnadyne's fail in two years of having my rig. I use a Good Sam GPS from Camping World - it's been very reliable. In addition to having a backup (especially if you wholly rely on the GPS to navigate), I prefer to use the in-dash unit for the cameras only when driving. If you have the side-view cameras, whenever you signal a maneuver, your in-dash screen will switch to the camera and off your GPS. It stays on the side view camera for several seconds before switching back to the GPS. If you're in a city with complicated interchanges, you'll be staring at your camera when you're wondering where to turn. Having the stand-alone GPS as a second screen eliminates this problem. I've blown many a turn before I changed to use the two screen solution...
If your slides have cables in addition to the hydraulic cylinders, you need to have the tension in the slide cables checked periodically. I didn't think of this, and the cables stretched to the point that the slides sagged so badly that I could not open the basement doors fully. It also affected the angle the slides sat when retracted. The slides came in so steeply that the crown moldings shattered when they hit the inside roof of the coach. The cables will stretch when they're new - you may want to have them checked after a few months of use. After that, I'm hoping they don't require more than annual adjustment.
Find a good RV shop to perform maintenance and repairs. My experience is that for chassis-related issues, Freightliner dealers turn the work much faster than an RV dealer. If you join the Freightliner Chassis Owner's Club, you'll also get 10% off repairs at Freightliner. They're all over the country, and some of the shops operate 24/7/365.
If you have trouble getting things fixed, call the Forest River Diesel Motors Division. They really helped me out. The first RV dealer I took mine to for repairs was sitting on my unit for months, and breaking more things than they repaired. Mike from FR tried to work with them, but was unsuccessful, so he sent a driver to return my rig to the factory for repairs. They fixed everything and even offered to drive it back to my house for me (1200 miles one-way) all under warranty.
Just curious, you're picking up your Berkshire in Michigan, and returning to California? I live in Oklahoma, but when we wanted to buy the Charleston, the only two that were available were in Michigan. We drove to Detroit to pick it up and had our baptism by fire on the drive home.
I wish you well! Drive safe!