What are the regulations for lighting fixtures around an airport?
To start you off there's these two: 

14 CFR Part 139 - Certification of Airports and

14 CFR Part 157 - Notice of Construction, Alteration, Activation and Deactivation of Airports.

Part 139.311 covers all the lighting related requirements.

Part 157 is there just so you can inform the FAA about the changes you're going to make in the airport.

for specifics about LED lights, I would suggest looking for Advisory Circulars with LED lighting for airports in particular.