Besides providing improved bracing with a 4 point, the main difference is that the 4 point requires modification/bending of metal Auto Trans Fluid lines in order for the 4 point to fit, whereas you don't have to do that with a 2 point. For guys with sticks, it's a non issue.
I can't answer that. I can only tell you that my 89 LX (which, unlike the Saleen, did not have any factory bracing like that) was a completely different car after the strut tower brace, K member brace, and sub frame connectors.