Australian/British Dual national coming to Belgium (Brussels)

Hi all,
To introduce myself I am currently living in NSW, Australia.
I have an IT background (Sytems Admin) and qualifications as an aviation fire fighting specialist working with aircraft such as "Elvis" the Erickson Aircrane amongst others.

I am considering a move from Australia to Belgium to work (employment to be found on arrival) entering on my UK passport but needing to retain my Australian residency due to property ownership in Australia.

Can anyone provide any information/advice on health insurance and residency registration. I am aware Australian Medicare has reciprocal arrangements with Belgium but might this be an issue entering on a UK passport. My understanding is that to even rent one has to have a residency card from the relevant commune you want to live in and what documentation I would need to source before I leave Australia.
I was told I would need some sort of judicial record but is this sourced from state or federal police departments.

Any other advice or information happily accepted of course

Cheers
Sean