Hey Buckhunter,
Welcome to SMF. This is the right place to get your smoker build done the right way. Some pictures, dimensions would be helpful.
Thickness of the RF plate is usually recommended at 1/4", but this depends upon your budget, material availability. The thicker it
is the longer pre-heat time is, but your temp fluctuations will be less. Make sense? More material is more thermal mass. As
far as door recommendations, a lot of that depends upon personal preference. Will you be cooking butts, brisket, chicken? or whole hogs?
Wider doors are better for larger cuts.
Hope this helps out.
RG