First, welcome to the Keystone Forum. Secondly, I wish that your experience with your first, brand new RV was more pleasant than what you have described here. I am assuming that you didn't notice any problems around the slide area floor and adjoining walls when you did your pre-delivery inspection.
In regards to your damp mattress....... that may have been caused by an excessive buildup of moisture/dampness around the bed area and because the mattress was sealed in a plastic wrap, condensation built up inside with nowhere to go.
You might want to refer to one of Flyguy's earlier posts about water penetrating the side wall from below because of exposed wood/particle board edges near the wheel well area. This may have happened and your side wall became saturated with water, softened, swelled up and began to separate.
As far as your warranty is concerned, I don't think you will get far with Keystone. You can go to their website (
www.keystonerv.com) to find out how you can contact them. Your 1 year warranty with them has expired and I would be very, very surprised if you will get anywhere with them at this point. Have you tried going back to your dealer? If your dealer doesn't have anybody to work on an RV, I would think that they would find you someplace or someone who can.