Wall build questions

[FI 4 life]

Hey guys I'm 19 and gonna start on my first wall soon in my tahoe. I have a few questions for someone with building experience. I'm doing 8 b2 audio is 15's in a 4th order. I'm getting a design made along with a full cut sheet. The first question is how do I build a strong roof before the shell? Do I just use sound deadoner? My second is when building the shell would I do it out of 2x4's or mdf? And when putting the floor in would I bolt it to the cab or use special screws