The floorplan lets the dealer carry a lot more cars in its inventory than it can with a cash basis. It pays for itself if the cars are in inventory a short period of time.
The rear glass issue is covered often on this forum. It is a common problem. It is expensive to replace a top if you can get one.
Be wary of Bonham.
Check autotrader.com, cars.com, ebaymotors.com and other online sites and I bet you can save some money.
While some of these cars have problems to be fixed. I don't remember anyone with with multiple problems on one car. These are good cars and I haven't heard of a lemon Crossfire.
Good luck