Would Delta Skymiles and Delta Skyclub be considered promotion techniques or a product they have?

Answer 1

They are considered both. Skymiles are needed as a frequent flyer program to attract business. Customers who accumulate a large amount of Skymiles have a chance of upgrades. This promotes the airline and keeps up with competition. The Skyclub is a relatively quite area with meeting rooms and bars and WiFi so that business can be attracted. It is thus used as a promotional tool but it is also a product in its own right and appears on the P/L balance sheet.