Correct as there are differences from office to office so your local Immigration Office checklist is the place to start then come here with any questions
yes, 2000B whether 8 days late or 8 months late so if already day 8 or later forget about it until the next extension is due otherwise you could pay another 2000B for another missed report in the same period
Normally your first Extension of Stay based on a Non-O issued in country has to be at the same Immigration office that issued the original Non-O. If you are travelling to Phuket, for example, you can ask them if it is possible to get your first extension there,
the Non-O can be obtained in country if the applicant is lucky enough to have a passport from one of the countries whose Embassy still does the income affidavit