Not completely clear at this time. There are indicators that the DTV might also be available in Thai consulates in some third countries. The next couple of days will tell.
You don't ever need to extend, if you are okay leaving Thailand every 180 days (for a few hours). You don't have to re-apply in between, you can go and come again for the whole 5 years.
The proof of residency is limited to the E-Visa applicaitons, and merely serves to make sure people make use of the correct consulate responsible for them. Having said that, there are visa known to be only available in your home country (as the METV). So, it might me that the DTV will be as well. But might also be available for paper visa in third / Thai neighboring countries.
I guess. It is a bit wierd, indeed. First, they crack down on people "abusing" ED education visa, now they open the gates for basically everybody with (potentially borrowed) 500k THB on their bank account.
I didn't know that. Interesting. Maybe they meant only the LTR of the "Highly Skilled Professionals" category for those working in Thailand for a Thai entity. Or all LTR holders working for a Thai company. Sadly, that would exclude the LTR for Remote Workers, where they scrapped the possibility of (additionally) working for a Thai company / work permit.
I personally would not hold my breath on that "music festival" example. I have heard of several consulates telling people that any booked leisure activity should be at least of 6 months duration to qualify. But that isn't official yet, either.
Yes. There was much confusing and wrong information spread. But now we know, you can enter as many times as you want within the validity of 5 years and this stay more or less permanently (with few border bounces).