There's no visa amnesty nor STV anymore. If you want to enter as a tourist you have the visa exemption for 45 days (30 from next month) or applying for a tourist visa which is 60 days.
2) it ends on 27 September, not 30th. As to when, if, they announce it is being extended or not...anyone's guess! Last time they announced a week or so in advance, previous time they announced it on the afternoon of the day it was ending.
Check your local Thai Embassy website about 2-3 weeks before your departure. Things change daily here so what's required today might not be the case in 4-6 weeks time.