All info I can contribute, is that they mainly operate short haul flights to the Lowfeld out of FAJS. Good if you live, stay and want to operate out of Joburg and be back at home by early afternoon.
You will need close to 800hrs at least before they even consider - it usually states requirements on their website. Usually means starting on the Van or BE58 because there are many in front of the cue to fly 1900. People wanting to use FedAir as a stepping stone will be treated as such and be offered a low salary package (similar to flying a C210 in Nam or Bots) - the longer you stay with the company and prove you loyalty and fit in with the crowd, this will eventually change (so they say). That is one of the reasons, contract flying the 1900 was far more attractive for me from that point of view at the time. There is also a seniority system in place - new guys starting right at the bottom - will probably be different when you come with a lot of experience and there is nobody to fill the spaces on top - but I can only speculate about that because it was quite a while ago, things can change quickly... bottom line: if you are happy to make FedAir your carreer it may be worth it, if you have other goals as well it may be more financially viable to persue those instead.