Being an Australian (As stated) you can get entry into Thailand for 30 days for tourism under the visa exempt arrangement. There is no limit to the number of entries by air. There is a limit of two land crossing entries per calendar year. Land crossings are 30 days for Australians also.
1 year Non O based on Spouse can only be approved from Canberra. Sometimes they approve it locally under consultation but they advise it may be sent to Canberra and take more time.
It isn't a 7 day extension. If your application for 30 day extension is denied you get 7 days to leave. It still costs you your application fee of 1900 baht.
I suppose than, like immigration, each Amphur is different. We were not at our local. We had to do it in Bangkok. We had a few issues with the witness requirement but that was sorted by a senior official.
I got married a year ago in Bangkok and showed nothing related to finances. It was all about having a notarised certificate stating I was free to marry. It was a fairly large department/main office.