Can I use a DTV to open a bank account and convert my scooter license to a permanent one in Thailand?

I think these days you have to use an agent to help you open a bank account.. It's getting very difficult to open one. It's very useful to have a local account to do payments to others using bank to bank transfers and also for shopping using the banks app.

Driving License: Fingers crossed on the 5 year driving license. I mean it’s a 5 year visa, so a 5 year driving license would make sense. But maybe that is exactly why it won’t be possible - too much sense. 😅 I am so annoyed of having to get a new DL every 2 years again and again with all the documents (residence certificate, medical, etc.) required. Even every 5 year is an annoyingly short validity for a DL and Thais need to do this annoying renewal, too.

Bank Account: I don’t think the DTV will help much with that either. Even with the LTR (which is actually meant for temporary residency) it is not a walk in the park.

When and where can we start to apply?

You don't need to make a 25,000 bank deposit, so no banking allowed. Get a Wise virtual card and a Schwab debit card ( refund all ATM fee)

Where will you be staying in Thailand?

The DTV is classed as a tourist visa I believe

You dont need a visa directly for driving licence as such. You need proof of residency which is obtained from immigration. Immigration will issue these if your on a long term visa or extension of 1, a DTV should qualify as its greater than 90 days and you have a permanent address.

We don't even have full access to the rules to actually apply for it so these extended questions you're asking are going to be difficult to reply to at this time.