I think it's more about continuity of staying in Thailand than the number of actual entries. If you are genuinely in and out with significant time out, then no limit. If you border bounce with no obvious means of financial support, they are going to think you are working in Thailand.
Hua Hin is a very good immigration office. You will need to report when you have a lease from your landlord. You do not need to report if you are away or leave the country. I used to go back to report in when I returned from Oz but they always ask "Are you still in the same place?" I say yes and they tell there is nothing to do.
I'm an Aussie that had an O-A too. Just do the border bounce. You'll get a free year with no hassles. Don't forget you need a re-entry permit if you leave during the second year.