How was this deck/fence panel built

My first thought would be to build the deck in individual 4x8 sections. So you build a frame out of 2x4's or 2x6's with one sheet of plywood on top and the insulation pre-installed between the framing members.

You would then set up your concrete piers and beams that would support the sections. If you use 2x4 framing for the pre-built sections, you would need more beams and piers, but the individual sections would also be lighter and more easily man-portable. Place the pre-built sections on top of the joists and screw them together from underneath.

When you disassemble, you just unscrew the pre-built sections from each other and the joists, take them out in one piece, and stack them on a trailer. Being 4x8, they are the perfect size to fit in just about any trailer or pickup truck and not too heavy for one or two guys to handle. Once those are removed, you can disassemble the beams and piers.

Holy cow I just went through this last summer with a house I bought...

Specifically, 2009 IRC section R312.2 states: Required guards at open-sided walking surfaces, including stairs, porches, balconies or landings, shall be not less than 36 inches high measured vertically above the adjacent walking surface, adjacent fixed seating or the line connecting the leading edges of the treads.

So yes most/all municipalities that are using 2009 IRC and above would require that you have your rail height 36" higher than the seat. Let me tell you that this is almost impossible to do without a ton of work (and having it functional and looking good). Most people don't want railings at 46-50" since it encloses the deck and is reaching the height of shorter women.

What did we do? We simply detached the bench part and made sure it fit snugly into the deck. Since it is not a "fixed" part of the deck it passed inspection. We were not concerned about small children because it was already 26" over the seat and had vertical backs set at 120 degrees.