W out being hands on, no way to be definitive about any of your questions, except that no, its not likely duoble hulled. Theres the lower hull thats been painted and the inner 'tub' thats got the seats, consoles and etc molded into it. Between them is a plywood stringer/bulkhead structure and flotation foam.
Didnt work last time, and as I've said numerous times, the prior poorly done repair makes it very suspect that there is more damage and water below decks in the foam then you think.
If its been repaired w bondo, below the water line, and the bondo is exposed to water, it'll absorb water and become a playdoh like mess.