Its constantly changing but the principle is you have a bond held for 3 years, you pay for training and you are not paid until you start line training.
It can add up. There are usually enough volunteers so its up to you if you are offered. The deal is offered. Take it or leave it. The next guy down on the seniority will take your spot.
It is what it is. Its the contract world. If you want free type ratings you need to stay away from contract work.