Residency on Isla Mujeres

Hi there

We're from Australia, looking to relocate in a few years.
Looking to speak to anyone who comes from an English speaking country to see how you go about applying for permanent residency.  As our children are older we would love to spend some time on the island (say 6 months of the year) and head back to Australia (for 6 months of the year).  Any ideas on how the residency works?

Also, my husband is from the UK and holds a british passport (resident of Australia now but only by marriage).  If we are going between Isla and Australia, would  he need to become a citizen of Australia to gain entry back to the country?  Any ideas on who I can speak to about this?

Will be looking for work just to cover rent and basic living expenses.  Would love an idea of how expensive things are on the island as well.

I can't see anything bad that I need to be aware of on the island. Anything we should be aware of?
The only thing that I think I might have some trouble with is access to money if I have Australian Dollars.

If anyone can give us some insight that would be great.

Cheers in advance - Michelle