Of course you need a proposed treatment plan and associated booked or proposed dates of further treatments. Spend less time rushing to get the visa and more time planning and providing a series of documents that legitimize your reason for the visa.
It's an absolute non issue, date of issue and date if application and valid until date are seperate entities. The rule applies to where you are when you apply, not to when it's issued. people apply too late for their visas all the time and don't get them approved till after they have arrived, they then exit the country and re-enter using the newly approved visa. Stop thinking so much.
why question my reply? I stated the requirement. The money also has to stay for 3 months after the extension is inked in and after that cannot go below 400k, then 2 months before you apply for your next extension you top it up to 800k again. But many just leave it untouched.
You voided your OA leaving without buying a re-entry permit beforehand. You'll need to start the process all over again, or apply for a 90 day in-country Non O visa, and then apply for a 1 year extension when you have seasoned 800K in a Thai bank for 2 months.
Once you have applied in Germany you could go to Thailand, if the DTV is approved then bounce out and return showing your DTV visa printed out to get stamped in for 180 days.