I'm presenting a topic on cargo operations for the capstone course in my degree program and have some of questions concerning Part 121 and 135 cargo operations...

First... since FedEx and UPS operate as a Part 121 Flag/Domestic carrier, do they abide by the crew duty days associated with Part 117? I was reading through some of the regs and if I understand correctly, operations under Part 121 Supplemental are not required to follow Part 117, but I couldn't find a clear cut answer for Flag/Domestic cargo operators under 121 Flag or Domestic.

Second... for the cargo companies operating under Part 135, do they follow the 135 crew rest regs or is there some supplemental for cargo operations I am missing?

Lastly... I am rather unfamiliar with how the operations of 121 carriers such as FedEx or even 135 operators conduct such operations. (ie, do the pilot receive a cargo manifest for all of their flights? What is done with the cargo prior to loading it on the aircraft? Do carriers have contracts with the USPS to transport mail? Or do small items such as envelops travel mainly by pax carriers such as Delta or United? etc, etc)

Any insight would be greatly appreciated!