Not everyone needs to go. 90 day reporting only requires the passport and the completed form. The person for the report is not required. Anyone can do it for you.
The agent who runs this group offers a 90 day reporting service. Check the pinned posts.
you must be on the status you are extending during the time the transfers were made in order to use that method to extend. Which means the transfers must have all happened while you were on a retirement visa/extension already in order to use it to apply for an extension. Therefore it's not possible for the first extension. Even if you have 10 years of transfers, it will not be accepted. Only embassy certified income or 800k in the bank.
to get the visa, it's correct. But that's only 90 days and from the Thai embassy in UK.
Once you're in Thailand immigration will only accept 800k in the bank or embassy verified income. The UK embassy stopped offering this many years ago. That means the only option is 800k in your Thai bank account.
it's been clarified about 500 times in this group. And the list of requirements immigration gives out says it as well. And it will probably be stamped inside your passport too.