Use the same PVC glue for everything. If you can't find MEK at the hardware stores start calling around to automotive and other types of paint stores. They might have some left. Use Acetone to prep, and everything must have all old glue removed. I used scuffy pads to clean up the old glue with acetone while wearing chemical gloves.
When gluing it back on the glue is only good in the pot for a short time. Therefore you need to glue the transom in first, then work on putting the floor back in doing so in sections, as you mix a fresh pot. Buy a couple boxes of disposable brushes in like 2", 1", and what are called solder brushes from Harbor Freight. The glue adheres the two pieces of materiel, and will not need clamping or anything. When the two parts touch with the tacky glue between they will be almost inseparable. The key is the temperature has to be ideal, with low humidity, and time is a huge factor. You have to work efficiently and fast. Sometimes two people are good to have...and a few straps.
Yikes! I just went and looked at the photos. It gave me nightmares from doing mine, except your boat is toast. The peeling of the plastic layers is the sign of death. You can't patch over that much material. Or so my opinion goes. It is not worth the time and money to fix a boat that could blow a chamber at any time. Sorry probably not what you want to hear.
As a guess I would say over $180 in materials, and probably close to 40 hours to do it right.
2 quarts of this glue is what I wound up using. There is also a video to watch on repairing PCV.