As far as we know, the new visa is 6 month per entry and not 6 month per year. But I second suggestions like Cambodia, a one year business visa is about $50. But then: you have no real use for a Thailand visa :P
Multiple entry tourist visa. Each time you get into the country it should give you 60 days. Two entries is already 120 days, and then you can extend another 30 days.
Does not matter if the embassy says so. The rules are the same for all. And not posting the link makes it impossible to verify what you have in the screenshot. The embassy probably simply does not like to process visa applications (hence the: can not apply) from people who have not retired. Perhaps they include an adidavit about retirement and income. No idea about that.
For a Non O based on retirement INSIDE of Thailand you only need to be above 50 and have the funds. No need to actually be retired (would not really make sense anyway).