Welcome, FLGatorGirl.
"Do the Mobile Suites (2009-2011) have real wood (not foil) on the cabinet face frames, wood panels, interior doors, etc?"
Our 2010 38TKSB3 is pretty much all wood (that I can tell) on the cabinets and such. As for wood panels, since ours is only 3 years old and has not had the "wear" of some others, I can't say the paneling is all wood or not. I think they are wood.
"I know this is going to be floorplan specific, but do most floorplans allow access to bathroom/kitchen with the slides in?"
You are right in that it will be specific to the floorplan. However, most anything that has a side bathroom (letters "SB" in the model number) will require the slides in the bedroom and the kitchen to be out. There are a few exceptions.
"Do many DRVs come either with a generator or at least gen prepped? Does anyone run the generator to cool or warm the 5th wheel going down the road prior to hitting the campground?"
Question one is hit or miss. Most of the DRV dealerships that we looked at (back in 2008-2010) did not order anything with generator or generator prep unless the customer ordered theirs that way. Question two is also hit or miss. While the generator would likely power the air conditioners while traveling, I would be concerned that the air flow around the trailer might cause generator exhaust to enter the trailer somehow. With heaters, since they are 12V powered anyway, those could run off of the batteries to keep the trailer warm, so long as one didn't spend lots of hours towing without recharging.
"How hard is it to change out the living room furniture?"
We removed the couch from the back of our coach and also got rid of the stock recliners (fabric) and replaced with other furniture. In our case, we bought a La-Z-Boy Reclinaway love seat to replace the two recliners. With them (and some other recliners as well), the backs are easily removable and by watching dimensions, can easily go through the entry door. Our couch has been replaced with a small recliner and a sewing center.
"If we stop just overnight at a Flying J, assuming the lot is mostly level, can we sleep as is or do we need to put down jacks or anything?"
I think most folks would prefer to at least put down the front jacks. I really can't say a lot as we are "static" full-timers that haven't yet retired to start traveling. Our travels so far have only been for a few hours one way, making it easy to get to our destination and set up properly.
Now, if you are considering used trailers, check our the website of Rolling Retreats in Elk City, Oklahoma. They are a mom and pop dealership that deals primarily with DRV products. Well, except for the trade-ins that they get. They have an excellent reputation among many of the owners of DRV's that I know. Look under their "Inventory" tab and go down towards the bottom of the "page" to see the used units.
http://rollingretreats.com/
Now, since they are in an area of the country were most RV's are likely towables, I don't know how much you could get for your motorhome if you are trading it in for a used DRV. You might want to try to sell your motorhome outright to get the best pricing.
EDIT: OK. I missed one for research purposes. One of the guys over at SOITC started a website that has a lot of information on it, including the DRV brochures in pdf files for a number of the model years. It is DRV Owners Manual.
http://drv-owners-manual.com/
Terry