As others have said non-public info won't be divulged, even in an interview. Some other things that are public knowledge:
- Reinforced & locked flight deck doors became mandatory - which has also led to other unintended consequences like the German Wings A320 suicide crash.
- Liquids control makes daily working life at an airport a challenge (although this was as a result of the subsequent shoe bomber in the same cause rather than 9/11 itself)
- Consideration of anything being a potential weapon e.g. cutlery
There were also some significant short/medium term economic effects after the shock - depressed traffic led to all sorts of things including the end of supersonic commercial travel, airline failures, depressed asset values etc. One effect turned into a positive for some though - depressed order books for manufacturers generated great opportunities for growing, cash rich LCC's to renew their fleets at scale and very cheap prices which (certainly in Europe coupled with deregulation) leading to the meteoric rise of Ryanair and easyJet.