for the METV you need a ticket out within the first 60 days and then a return ticket to Thailand sometime after that, and of course you can show your ticket home in 6 months, actually you can get almost 9 months out of this Visa if you time your border bounces correctly.
One in a thousand people are asked about it. Dunno if they'd use it to deny entry, definitely have 20,000 baht currency in cash on you upon entry. Also I'm not sure the IO would know what type of account it was in. So opening a bank app and seeing 500K in some type of account with your name might fly.
you ain't getting an entry stamp, you ain't entering. If an extension is denied then you still have whatever time is left on your current stamp to fix it or leave. So, don't leave it till the last minute.