Airline pay is based on block hours and minimum guaratee, usually 70-75hr per bid.
In my case, we get paid twice per month. The first check is a steady $900 the second between $2000 - 3000 depending on how I flew that month. I Upgrade at the end of the year and that will be a 30% pay bump.
The first check is an advance, the second is what you actually did the month prior minus the advance. It includes Per Diem, time over min guarantee and anything above else.
I fly mostly day trips so my per diem is less than if I flew a lot of overnights, but I'd rather be home every night.
Daily rigs are important too. It means if they use you for one leg in a day you still get paid for a full day. We have daily rig and it makes the flying alot more efficient because the company wants to get the most out what they have to pay you.
I'm not a Union fan, but the Unions actually have alot of horsepower even at the Regional level.