The insulation was rock wool just be careful around the locks and cables that you tape it all securely or the locks can foul up.
The panelling was 3 lots of 1/4 inch marine ply. I used 1/4 inch so I could get the bend of the van easy enough and I used 3 sheets so I had the strength to screw things too.
I think I used 1/4 inch and then 1/2 inch on the roof but cant remember. I know thats what I did to my van in the states.
The floor is Altro safety and yes capped and coved for obvious reasons.
Alltec do out vans with a spray coat of some sort which I am sure is much better, certainly lighter but I like the strength of mine so again I can fix things to it. Especially as my hose reel is suspended upside down and the racks are also suspended. In fact nothing is on the floor or fitted to it save the obvious, water barrels, water softener etcetera.
Best, Dave