Congrats on your new purchase. You have a good list to start with and have received some good suggestions.
I will second taking a lot of time on your walkthrough. If you have an RV knowledgable friend, bring them - if not still bring some for another set of eyes. Keep lots of notes and video. Have them run every system. If they run the heater - they can also run the ac even if its cold outside.
Don't feel pressured by the dealer (or yourself) to pull it off the lot with a promise they will fix issues later. You will likely get quicker service if it has not been paid for or delivered.
Zack and Donna plus Millie
2018 Montana 3160RL
"Life is too short to stay indoors, enjoy the ride!"