the SSC guys use the 25lb strength foam and 40 for the open B wings, although you could use whatever you can get. for the SSC airfoil, they are usually using the E-203. use a program like compufoil or profili to generate the templates. This is an awesome video on foam cutting, he makes t look so easy, but it is so easy to mess up a panel, have fun!
http://www.rcgroups.com/forums/showthread.php?t=462759

there is also a combat sub thread on this site, RCU. check it out