I’ve been reading and still have many questions. Please help me with my planning & reasoning.
I’m currently on an OA retirement visa from the US. I’m planning to switch to an O visa granted within Thailand.
Does each of these visas have equal validity and standing? I certainly would not want to have to go back to repeat the many steps to reapply for the OA visa.

To Apply for the O visa: Would I have to leave Thailand and return after my current OA expires? I was not planning on going to my home country to apply for a visa there. Does it matter where I go?
In the Proces: would I need to get a visa of some sort from a Thai Consulate perhaps in Cambodia or Vietnam? Advantages? Easy better SE Asia place to apply for visa— if one is needed?
Or can I just enter on the regular 30-45 days granted upon arrival?
Since I’ve got the money in my Thai bank already. When could I apply for the 90 day non O visa? Do I get to skip any steps?
Then after 2 months I would need to apply for a Year O extension? Is that essentially expanding a 90 day visa into a year O visa?
And.. Once it is at that type of O visa.
I’d need to apply for reentry (if I want to leave country and not lose my visa)?
And, eventually, 45 day before expiration, I could extend that O visa for another year. And repeat?