amp rack+AQ box

hello, I just got my AQ 2200 in and I plan on building an amp rack and maybe rebuilding the box. well first, for the amp rack should I use mdf? or is there another wood(maybe cheaper) that would work just as good? I would either paint it or wrap it.

Second, When I do that I might build a new box. I love the lows, the box now hits the lows pretty good, its approx. 6 cu/ft and tuned to approx. 35-36 hz. If I lower the tuning instead of gaining any low end output will I just decrease my output on the high end? and the sub is the hdc3 18" copper coils