Teardrops n Tiny Travel Trailers

I am thinking about getting a new cargo trailer and doing some limited conversion to it for camping/toy hauler.

It is going to be a 24ft x8.5 wide American Hauler.

The plan is to use it as a toy hauler for my Jeep and for ATV's, but I also want to be able to sleep in it comfortably, heat and AC.

I have been lurking in the forums and still need a few answers for when I get the trailer.

Insulation:
1. Do you add a vapor barrier before adding insulation?
2. How do you secure foam board? some type of construction adhesive?
3. Do you insulate over the metal wall studs or ceiling joists?

How are you attaching the plywood, with self tapping sheet metal screws?

These are just the beginning of my questions, so hopefully everyone will be patient.

Thanks.

Insulation:
1. Do you add a vapor barrier before adding insulation?
Someone else will chime in with an answer to this. I didn't use a vapor barrier.

2. How do you secure foam board? some type of construction adhesive?
I just cut it a little large and push it between the studs or ceiling joists then cover it with plywood, luan, plastic sheeting, whatever.

3. Do you insulate over the metal wall studs or ceiling joists?
I didn't.