yes, that is correct, first has to be done in person, but nothing stops you from filling in online and submit. Some people report succes. I received email it was rejected and had to do it in person, but I could print the filled in online form and bring it to the immigration office. And for DTV when you not extend online it will always be again the first time...
the 500K is still required, but mostly not checked, you can gamble you are not checked, but there is always a chance you are checked, depending on your situation. To prevent this check possibility, you pay for a professional border bounce company.
What is better depends on your situation. When you still comply to all requirements an in country extension might be best, saves money and a bit of time.
When you do not comply to the visa rules anymore, a re-entry is the only solution, best done with an experienced company to guarantee re-entry will be an easy process.
Tip: You can also fill in and submit the report online. In most cases for DTV holders you will receive an email online is not accepted and you have to do the reporting in person, but you then already have a completely filled in form, which is very easy to check at the immigration office.
Me too, money check is not too difficult, and in case they want to check I can still do remote work, logging in to the company at my laptop is also not very difficult.