Used mostly Soudal fix all to bond things together, and mastic in strip form for the roof light seal and bedding the railing in. Tried Sikaflex but found Soudal easier to work with. I replaced the inner walls with the skin off old ply doors (3mm ply) and used the door frames to replace most of the frame around the wall. Did the job about 5 years ago now, and it's still holding up.
Internal doors right enough, got some off a mate who was replacing his. The insulation is the original 1" blue stuff, I left it in place to dry out, and bonded the ply over it, proofed the ply with PVA glue and papered over it. Had to do most of the off side, the area and frame round the bathroom skylight. All bonding was done with sikaflex or soudal depending on price at the time. Papering done with normal wall paper proofed with PVA. Most of the frame wood came from the doors, but the parts that seemed to be load bearing, eg under the grab handle I used 1" thick marine ply.
Window seals were redone with soudal. Mastic for most of the outside stuff like vents and lights and the skylight. Soudal\Sikaflex for the rest. Basically, any part I thought I might need to take off at a later date was mastic.
The floor was a bit bouncy and was cured with the one part green liquid that turns to a dense foam. I dare say you could cut bad bits of floor out and rebond new bits on.
I've got a few pics of the job which I did while recovering from a long stay in hospital. I have nowhere to put them online.