Cacu, sorry, I thought I got back to you on this, I guess I just read it and meant to! :b
OK, lets see...
1) When I first built it, I was under the impression that ported subs could be stuffed like sealed could. I thought it would impede airflow, but had seen that people tried it so I did too. It sounded good, but then someone told me that it wasn't really the right way to go about it, and since I hadn't done any of the finish, and I had the speaker out again to do that, I figured I might as well redo the inside as well.
So what I did, was take a piece from the sheet of the polyfill (which came in a roll), doubled it up, and laid it out on the back (flat side) of the right sized piece of the foam (I had a bunch of this lying around, about 1" thick). Then with my sort of dual-dampening panel set up, I laid it in place, and staple-gunned it to the inside wall. Repeat for all inside surfaces. It made a huge difference from before when I'd put my arm inside and snap my fingers.
When I hooked it back up after I finished this, there was more air movement, and I think I got a bit more volume out of it. (Maybe not as much extension? But I'm not sure on that one. IT still pounds down low).
2) The bracing was just for convenience, I had a big port tube that I had to run through the bracing so it was cut slightly larger with a square-ish side, you can see it in the pics. And I didn't want to cut a ton of holes.
3)The amp took some planning to fit in. You can see it in my
wireframe diagram ... it fits just below the horizontal brace, on one of the sides that the vertical brace does not intersect. This might be easier to see from the wireframe as well.
Hope that answers your questions! A bit long winded, I know.