Re: 1982 AMF crestliner got it for free
Save the pieces of deck wood to use as templates for your new plywood. For new plywood, I would go with exterior doug fir ply and seal it with epoxy or poly and glass. Arauco ply, or what it's made of radatarian (sp) pine, is not as rot resistant as doug fir. Even if you seal it up it's going to be more susceptible to rot, any staple or screw hole not sealed up will allow moisture in, then the rot begins. I do agree that Arauco is some nice looking ply, but I'm not sure of the rot factor, long term. If Plydek XL is available in your area that might be a good choice for plywood as it's a treated marine plywood, used for pontoons and boats. It's kind of spendy, but you don't "have to" seal it up with epoxy or poly and glass. Oh yeah, don't use normal green treated plywood, it'll eat your boat.
That foam looks water logged, and with the condition of the wood, that would make sense. Do some core samples (piece of plastic pipe with teeth cut on the end, twist down into foam) and see if it's water logged. If it is, rip it out and replace it with sheet foam or EZ's favorite, pool noodles.
To remove the residual carpet and glue off the aluminum, soak some paper towels in lacquer thinner, lay them on the fuzz/glue, then cover it with a garbage bag so the lacquer thinner doesn't evaporate quickly. Let this marinade for 15 minutes and the stuff should easily wipe off. The fuzz areas might require a second treatment as the thinner isn't laying right on the glue. I bought a 5 gallon can of lacquer thinner for my project and used most of it. I would do a test spot to make sure this works with your glue, before buying a 5 gallon can. ***CAUTION!*** use a respirator and plenty of nitrile gloves when doing this. I doubled up the thin nitrile gloves and when the top one shredded, I'd put on another. Harbor freight has nitrile gloves pretty cheap, I'd get 2 boxes. (I tried a set of heavy "dipped" nitrile gloves, but they only lasted an hour or so. The tin ones worked better, even though the lacquer thinner eats them pretty quick.)
What you are doing looks pretty close to what I did on my 1800 Superhawk, good luck and have fun with the project.