Either by talking to people that work there, asking on here or more often than not PPJN normally is pretty close.
In theory the normal model would be basic salary plus things like sector pay and duty pay. These can vary quite a lot with some companies going for high salary low sector pay, others for lower salary and higher sector pay (such as Ryanair employees, who are not to be confused with their many contractors).
If you end up contracting either directly or more likely via an agency, this is when you may often get the no salary, only paid by the hour type of deal, but this is less common, with Ryanair probably being the main airline using this model.
With regards to estimating times for line training etc, it just is very difficult to say. I think there are still some bases in Ryanair that operate 6 sector days, the majority do 4 sector days and some only do two sector days. Depending on how many line trainers they have at a certain base, you could end up doing 15 4 sector days in a month, maybe with a couple of 6 sector days as well, or you could do like 8 two sector days, obviously you can see how this drastically changes the time it takes to complete a fixed number of sectors.