The only thing I remember reading is that not every country gives you a NON imm OA visa every time. You have to check this with the Thai Embassy in y'r home country.
Don't think so concerning the last bit. After that second year (need a re-entry permit if you want to leave and come back) you can ask for a year extension (with health insurance of the whole period of that year extension). So the only difference between a year extension based on NON imm. OA and NON imm O is that health insurance requirement.
Aha, there are 2 different visa's they call long stay. The non imm O-A indeed, but here we talk about a non imm. O, so without the 'A' ! That's maybe the misunderstanding. With the non O-A you immediately can stay for a year. Also 1 extra year with a border hop just before that first year expires, when you have y'r healthcare insurance covered for that year.
I think there is a bit misunderstanding between the words 'Visa' and 'year extension'. When you have a visa (non imm. O), you can enter Thailand for 90 days. When you entered, y'r visa is void. It gets a stamp in red 'USED'. So you don't have a visa anymore. To get this visa in y'r home country, you can use y'r home country bank for income verification. After e.g. 60 days in Thailand, you ask for a year extension at Thai imm. The first time you do this only then you need 800k฿ in a Thai bank account. But it also has to be there already 2 months before ! So when you enter Thailand, you have to open a Thai bank account as quick as possible and put 800k฿ in it. Then, if you want to change it to 65k฿ a month for the second year extension instead of the 'locked' 800k฿, also start transfering (international) 65k฿ a month. Then this second year extension you can use (bankstatement) these 12 transfers of 65k฿, to get it and only then you can take out y'r 800k฿.
Watch out. 12th is a Thai holiday. Also watch out, you need a re-entry permit (form TM8) to keep y'r year extension alive when you come back. Also can do this on the airport but need some more time.