Oz is a bit desperate for instructors at present so you probably wouldn't have trouble finding work.
I cannot speak to immigration issues.
Try Redcliffe Aeroclub for your FW conversions and there also seems to be a fair bit of RW stuff happening from Redcliffe too these days. Redcliffe is northern bayside suburb of Brisbane.
I cannot help but think, however, that you will have better employment prospects at home...perhaps work there for a year or two and get some turbine RW command hours and then come out to Oz and instruct initially before moving on to other things...perhaps tours out of PNG. PLENTY of opportunity in PNG for RW pilots on mth on/mth off work. Requires a few 1000 hours though due nature of work...lots of high DA/Long lining etc...think a tropical BC.
Best of luck.