I read somewhere that you can only do the visa exempt entry 3 times within 6 months for a total stay of 90 days. Is this right? If this is right has anyone tried to use another passport for another 3 entrys (i have Aus and UK ones). My plan is to stay for 6 months and am tossing up the border runs or getting a tourist visa. I'm sure the visa would be easier but wouldn't mind jumping to a new country close by every month for a look around before coming back.

A Visa would be easier, 30 days visa exempt would only be issued at the airport, and you would need a plane ticket out within 30days, a multi entry 'o' visa would give you the opportunity to do any adjoining country visits by land rather than air, as would a two entry tourist visa with a reentry permit.

There is NO LIMIT whatsoever for 30 day/15 day non-visa stamps. You get 15 days for a land crossing, 30 days by airs. The rule you are referring to is HISTORY. Long gone. Not an issue now. Next ...