I clicked the link and am not sure what specifically you found from it. As the other comments mentioned there is no such 90day limit rule within 6 months. You also aren't entering on a tourist visa, but via the visa exemption scheme which is now 60days. There are no issues with your planned itinerary.
If you stay over 180 days in a calendar year then yes you become a tax resident based.
However, if you have a DTA then that can override that. Especially on a tourist visa, you will likely be a tax resident of your home country as well. So will need to read your DTA and work out which country you are deemed a tax resident of.
there is no written limit on flying in visa exempt, but immigration officers can and eventually will deny entry to those who abuse the system. Sometimes it's after 4-6months, whilst some make it years before encountering issues.
they use to have these coin counting machines at banks, they got rid of them. So clearly it wasn't worthwhile for the banks. There might still be one left at SCBX Park.