Have you ever held a TIG welder before ? I'm asking because these questions really scream "I want a shiny part, i have no idea what it does, how it works, what i need, how i want or anything else that i should have done research on, AT ALL !" to me...
But that part aside. I made my own ffim, had a little experience with TIG welding aluminum... about 2 hours total. And it shows. Which is why i'll probably make another one now i know what to expect and look out for.
First of, i use 3mm thick aluminum for the plenum, 10mm thick aluminum for the base of the plenum (where the runners enter the plenum) and 15mm for the TB Flange.
Throttlebody, well i used the stock tb, including linkage and cruisecontrol. Yes cruisecontrol

. You could pick up a aluminum 90mm TB but you'll have to do some research or hope for some more replies on this thread for info on how to use the stock TPS with a non-stock TB.
Vaccuum is simple, one big port and a vaccuum manifold.