None of the developers are likely to have tried a site installation (to my knowledge).
It looks like you’ve found what you need. The “important bits” are the release executeables, symlinks to which will land in the bin directory. (They’ll all end in “release”, like “FloppyTail.linuxiccrelease”.) The actual executeables are where you specified. The rest of the files in build are the library files, which aren’t particularly important with statically linked executeables.
I use 64 bit for pretty much everything, and that’s true for a fair number of developers. I think you’re unlikely to see problems. Rosetta trajectories are supposed to be constant within hardware and RNG seed (and they are at the moment!), but you may see different trajectories with the same RNG seed if you change hardware.