If you apply for an annual extension and your passport is not valid for a year, you will only receive an extension until the expiration date of your passport. That means you need to renew your passport a few months before you plan on getting an extension during the expiration year of your passport.
Wise is not a bank. It's a fintech service. Where did you transfer the money FROM? That was more likely a bank account. How long ago did you transfer the money? Perhaps you can show the bank statement from there if it was a recent transfer.
To select your arrival date, there's a calendar to choose the day. That calendar only lets you choose a date within 3 days as your arrival date. 72 hours isn't really relevant. It's any time within 3 days of your arrival.
If you use a safe entry agent for VIP fast track, there is no "pushing your luck" as it's a pre-arranged guaranteed entry. It just gets more as more expensive the longer you've been in Thailand.
1) I believe the embassies and consulates in the US only care about the balance for the most recent statement.
2) no reports of that happening but always subject to change