In a sense, it remains a grey area, but the Thai authorities have finally decided - you don't need a work permit to work remotely and they've created a visa called the DTV to allow remote work.
However, if you're only coming to Thailand for 2 weeks and wish to work remotely, then you can and don't need to go through the rigamorale of applying for a DTV as your stay is too short to make it worthwhile.
That is, unless you wish to come and go frequently, then it might be worth it.
However, for an actual "digital nomad" who is jumping between countries and doing a little bit of remote work in between, that's fine to do on a visa exempt or tourist entry as you'll be moving on to the next country afterwards anyway and have no intention of residing in Thailand.
The DTV was basically designed, in part, to provide a pathway for longer term residence to remote workers.
I filled one out just a few weeks ago coming in by land from Cambodia. However, it's not so bad at land borders (unless you're at a busy one) because chances are you'll be the only person there, needing to fill one out (and indeed, I was). Apart from my family and I, no one else was crossing the border at the time I was and Thais have not been required to fill out the form since 2017.
Yes but don't forget the yellow fever vaccination certificate. They'll want to see a copy of that to enter Thailand as you're Brazilian / coming from Brazil.
I have no idea whether a medical contraindication certificate for yellow fever is accepted by Thai authorities. Singapore requires those who present such a certificate to quarantine for 6 days!
Yes, that's what I've noticed too. Vientiane has long been this way. I suspect that's why Vientiane is a bit stricter than most other nearby countries (other than Malaysia and Singapore) when it comes to getting the DTV or other visas...because they want to nudge you towards paying for an agent.
I'm not sure about that. Both visa classes state "employment prohibited" on them, meaning no employment in Thailand. You can, certainly in practice anyway, work remotely on ANY visa or visa exemption.
Not sure where you're getting the idea you absolutely need a DTV to work remotely here. Ideally, you should, particularly if your intention is to spend an extended time in the country or even (sort of) live here.
If the authorities were actually hunting down those working remotely and fining the ones on tourist visas or exemptions (despite the fact the DTV has the same conditions on the visa), no one would dare come here as a tourist and send an email and this would greatly affect Thailand's reputation.
In short: the authorities don't care about remote workers unless they're taking away local jobs or people are doing something illegal or immoral, even if it doesn't involve Thailand directly (such as selling sexual services, selling weapons or running an online casino). They've essentially said: we are OK with remote workers / digital nomads. If you come for a short time, no need to do anything. If you come for an extended period, please get a DTV.