I party agree on that. If the DTV becomes as popular as it could be, then there would certainly be more competition in terms of resources like accomodation etc. I am not a big fan of overtourism. But I would hope that longter term visitors would be having less negative effects than other groups of tourists.
The Thai eVisa website has issues right now - try again tomorrow. There is a section on the website that lets you check: "Am I eligible to apply online?". Either yes, then proceed applying for a visa online, or no, then proceed applying for a visa directly with your closest Thai consulate in person.
Yup. Gotta extend your LTR for that other 5 years before the first stamp expires. And that extension for another 5 years can and will only happen in Thailand (even only in Bangkok). One of the things I found annoying with the LTR.
I am not aware of such a problem with Thai visa. The DTV is a 5 year visa - how long of those 5 years you choose to spend outside of Thailand should have no effect. Neither with the LTR for all I know. The LTR comes initially for 5 years, too.
Being eligable for a visa category is not the same as being eligable for using the eVisa system. If you are not eligible for eVisa, then you have to get a visa the old fashioned way by means of a paper application form and showing up (or sending your passport in) at an consulate.
Yeah. Some visa can only be applied for in ones home country / country of residence and not in 3rd countries. Unclear, yet. I would it find it likely that the DTV is one of those visa - but I don't know for sure.
Many local Thai embassy / consulate sites have not updated their information on this, yet. Give them a few days. If you are eligible for eVisa, you can go ahead. Otherwise, wait for instructions of your local consulate website.