The visa is easy, but is multiple entry so have to do a borderbounce every 3 months.
An extension of stay based on marriage needs a bit more paperwork, but you do 90 day reports instead of borderbounces.
One important thing to note, when doing an extension based on marriage, you have to sign a declaration, which basically says, if you split up with the missus, you have 5 days to leave thailand...
Safer and easier to get a new visa each year. Also if you do a borderbounce just before the visa expires, you get another 90 day stamp, so 12 month visa gives 15 month stay.
Tm30 is the responsibility of a property owner, for reporting of a foreigner staying on their property. If you are staying in a hotel, they should've submitteded within 24hrs of your arrival. Nowadays they do online, so you should already be in the system... Failure (by the property owner) is 4,000baht fine, per day, not reported... Property owner, not you