IMHO it is designed for multiple 180 day stays and it is a tourist visa. The question here is the frequency of entry and number of times per year. Yes they want long stay tourists (greater than 60 days). But I expect it will change over time considering a tourist would become a tax resident after 180. I'm sure they would prefer the tax revenue... Time will tell. Check back in a year or so.
IMHO, it is the entry requirements that could change. Nothing will affect your current 180. But policies may change to only allow 1 every every year. Will still be valid for 5 yrs.
I believe it needs to come from the district where you reside. But your residence can be the last place you stayed. When I did it they wanted copy of the lease agreement along with signed copies of the landlords Id. I got certificate immediately by paying a couple hundred baht for expedited service. Don't think that's available at all offices. You need a copy of the registration of foreigner residing at the same location as the lease agreement.
I don't think you can get a reentry on the initial 90 day non-o, only on the 12 month extension. If you leave, you have to start over until you get your 1st extension.