A question of exhausts

Shamrock

I have a 2011 that I just installed the K&N typhoon. The engine sounds beautiful with slight pickup. Of course I want more. Right now the dealer I work with is attempting to get a license to import akropovic, which will take a few months to get. He offered in the mean time to install headers and catalytic converters (stillen) until the the exhaust arrives. Some questions.
1. Does installing the headers/catalytic without the CBE cause any damage to the engine? Is it possible to have this setup all the time?

2. Is a tune (up rev) necessary for the above set up and if so how much does it improve the system.

3. Let's say hypothetically headers/catalytic plus the CBE gives the car an additional 30 hp how much is from the headers/catalytic alone?

4. Is an upgraded CBE truly necessary over stock when switching headers/catalytic? Or is mostly a question of sound.

Thanks