Have you got your ATPL subjects out of the way? General Flying Services will not consider you unless you have. If you do, not a bad option, but you have to compete with the Swinburne & RMIT students.
If you do get the job with GFS however, quite a good steady stream of work with their mainly big contract clients. You also get to work with a pretty good bunch of guys.
Doesn't hurt to try, but I suggest you make first contact with the management before you commit yourself to at least make yourself known to them. Ross Carrington (Chief Pilot) or Phil Betts (CFI) would be the ones to speak to. As always, they will say 'no promises', but at least they won't be meeting you for the 1st time on your flight test, your chances of a job may be a bit higher then.
As for transitioning from a 172 to a PA28. you won't have a problem. The PA28s are easy to get used to. A couple of hours will do the job. So if you want to consider Wings, the new aircraft should not be a consideration. Hope this helps you, good luck.