Re: Were they paid?
Some sort of monetary system is definitely in place.
From TOS: The Apple--
KIRK: Trying to get yourself killed. Do you know how much Starfleet has invested in you?
SPOCK: One hundred twenty two thousand, two hundred--
KIRK: Never mind.
Moe: I'll take the blonde!
Larry: I'll take the brunette!
Curly: I'll take the Black and Tan!
--Wee Wee Monsieur (1938)