I am running a new exterior line to a carport to install two fluorescent lights in the ceiling of a "V" shaped aluminum 2 car carport. The underside of the carport reaches very hot temperatures during the summer months, metal parts are burning hot to the touch. I undersatnd I need to use exterior rated devices with GFI protection, etc. what type conduit should I use? The difference in cost of EMT vs. rigid donduit is substantial, will EMT be okay, or must be the heavier walled rigid conduit?

If you are planning on having the carport indefinitely, you might go with the metal. Even if it is rated to take it, the heat might eventually get to the EMT.