Simple answers are: no, no, no, and probably yes. The 4th item (if provided) will be a stinky slinky that'll last you about 2 trips before you'll want to invest in a more robust sewer hose. Everything, outside of what's bolted down on your coach at time of delivery, will be up to you to purchase. There are many lists on this forum (
here is a recent thread discussion) and others as a guide of what you "may" need to buy. Some things are "recommended", and yet other things are "required". Everyone will have opinions on which is what. I'll get you started with my "required" items:
1. Surge protector
2. Stabilizer jack pads / leveling blocks (or 2x6 wood plank cut into 10 inch sections)
3. 50 foot drinking water hose
4. 15 foot of quality sewer hose (Camco has a few brands)
5. Cordless drill with scissor jack socket (3/4")
6. Weight distribution hitch with sway control
7. 50 amp to 30 amp dog bone
8. Small carpenter's level
9. Basic tool kit
10. 90 degree elbow for water hose
11. Water regulator
12. Pen and paper (to write down things you may think are required or essential) after your first shake down trip.
Roof vents on RV's are pretty standard at 14". Any of the brands will work with OEM vents. I installed a MAXXAir 2 cover and it was relatively easy and straight forward. As far appliance insect screen covers, manufacturers don't recommend them as their thinking is they reduce air flow on intakes and exhausts. In my +1000 RV storage yard, I see very few screens and vent covers applied. I live in Michigan, but YMMV.
By the way, welcome and congrats on your new Coach.