Subwoofer Box Question's + Other's

Ok this may be one of the dumbest post yet, but I kinda need to know what kind of wood most people use to build boxes? I going to order a Audioque HD 12 or 15 more than likely I will probably go with a 12". Seem's it perfom's according to them identical to the 15". Plus I will always have room to add another 12" if I need so. I haven't really decided yet, but I have heard it's what I need to accomplish my goal..

 Also I have never had any sub's that have dual voice coil's so I don't really know how to pick if I need 2/2 ohm or 4/4 ohm. If I decided to later to add another 12 to a 2 ohm sub how many ohms would it be then? I know it's according on the amp I choose, but I would like to get a sub that can be wired to different ohm's. So I want have to buy another amp etc when I upgrade. So I guess the main question is how many different way's can a dual 2 ohm be wired and how many different ohms can I get  if I add another, and the same thing for the 4 ohm. I notice alot of amp's don't seem to push out over 400-500 rms on 4 ohm subs. Which these sub's need around 900-1200 rms to push. Can a single 4 ohm be wired to 2 ohm or can a single 2 ohm be wired to 1 ohm on these sub's?

Also are there any calulater's out the that will switch cubic feet to inches so I can get some box measurment's for this.Cause I have never measured in cubic feet.

Start here, including following the links:

https://www.the12volt.com/caraudio/boxes.asp