yes, your mentioning on the birth certificate in Thailand is NOT enough. You will need a court order by the Thai Family Court that you are the legal father. After this, you could actually achieve a longstay permit in Thailand, based on being the father and support of a half Thai child.
technically no advantage (you DON'T need a 90-days insurance, you will find this out once you apply by the E-visa system). The financial proof however on immigration is 800.000.-THB instead of 10,000.- US$ . . . . . "Required documents to upload in the system (Large and clear JPEG or PDF format):
Passport Biodata Page (Must be valid within 6 months)
Photograph of the applicant, taken within the past six months.
Flight itinerary to Thailand. Itinerary must include the applicant's name, flight number, and date of traveling.
Checking or saving bank statements (every month in the past 3 months) with an ending balance of no less than $10,000 that shows the applicant name.
Passport pages containing all travel records for the past 12 months. "
" I would get a non o except there is an insurance requirement in my country for a non o" . . . . . . . . gladly to say, then you probably missed that the 90-days health insurance requirement for application to the "90 days Non-imm-O retirement visa" has been discontinued
after 9 months with the multi entry Tourist Visa, it is OVER for a while. You cannot do visa exempt entries right after these 9 months on a METV. You will most probably be denied entry.