As for the CFI, he has belted round GA for a while, RPT piston company, big training outfits, even owned a couple of aircraft and is a nice fella.
If they are employing casually, make sure it suits. Forget about the Metro or J41, as your job is an instructors' one.
That's All you can ever expect. 
The opportunities will come when you have the runs on the board.
There are carrots everywhere guys and this place is no different
The sniff of Kero will allow companies to employ people on a casual basis, that otherwise they would not be able to. Sounds like these are Full-time jobs and the company wants flexibility with it's workforce. J41s' and Metros' allow them to employ casually, as Pilots will accept Casual, thinking they will get on the kero sooner or later.
If Mum and Dad can fund you, or you are rich and can support yourself, sound like a great opportunity as a
Casual Instructor with Carrot prospects 
If the shoe fits, wear it.