I would stick with a panel filter unless you want to experiment with throttle bodies and stand alone ECU`s. You would need to make your engine a screamer before you would find power another way
I think he may have set the fuelling on the conservative side to help with the run in period. He may well be right and when you get on the rolling road again he will set it up for full power. Be patient
I use a sharp chisel on the flat, or what remains of the flat, to split and open up the nut. It usually comes off with pliers if you do it correctly and it saves the stud thread
You can apply for your race license from the MSA... a google search will give you the web site. and you can apply for the "go racing pack. It will contain the "blue book" which has all the regulations in it.
Dont go there... you need expert tuition. Give my sponsor a call. He is Matt Thorne from Mtech Automotive in wiltshire. he will be glad to advise you on what to do next. tel 01373303033