You may or may not have read my "Palazzo Review" but the drawers coming open is an issue on mine and on a similar one I test drove so it has been around a while. It is a shame that it has not been fixed yet. The catches are on the bottom of the slide and must be all of the way in to work as designed. I had to raise the backs of the slides to get the catches to work at all. That was not enough so I added magnetic catches. I am still not sure that it is enough and the drawers are hard to open. I recently replaced some drawer slides in my house with some "self-closing" slides I got from Home Depot for about $18 a set. These slide pull the drawing in the last inch of travel and I am thinking that they would be much less likely to just pop loose on bump the way the original slides do. I am going to try to buy a couple of sets soon and try them out (after the T'day holidays and I get my coach back from other repairs).
My list was not as long as yours but I do share your dissappointment that so much was left for the owner and dealer to do. However, most RV owners I have talked with tell me that this is common and even worse with some of the more expensive (and complicated) rigs. I have found the Thor service department to be very helpful. The nearest CW is not close or convenient for me so before purchase I asked if I could take it elsewhere for service and was assured that I could and I am doing that now with the issues I have not been able to fix myself. If it would help you out to go to another dealer you might want to ask Thor about doing that.
I am also having issues with the large slide on the left and need to take it back in to finish the project. My coach is still usable and I needed it for a trip before the dealer was able to finish what he was doing. I think that he is going to have to upgrade the motors. I have wind noise right behind the driver and recently noticed that the seal underneath the slideout is not contacting both sides for most of its length. I hope that they can fix it and make the coach both quieter and less drafty while travelling.
The bag in the bottom of the slideout is to protect the plumbing and electrical service from wear as the slide goes in and out. It should have little or no effect on draftiness. If it is torn it needs to be replaced and whatever made it tear needs to be fixed.
Good luck and keep us posted.