NHR with Portugal limited liability company

I'm an American considering taking residency in Portugal as an NHR. I have been researching various aspects and ramifications of the NHR regime, and still haven't clarified a couple of issues so thought I would ask and see if anyone here has any guidance.

The first question is whether I would be likely to qualify for the High Value Occupations 20% tax rate for self employed persons as an internet marketing consultant to businesses (US clients only.) It concerns me that this determination will apparently not be made till several months into residency.

I see in the list at https://dre.pt/web/guest/home/-/dre/123 … /maximized
(Google translated)

25 - Specialists in Information and Communication Technologies (ICT)
31 - Technicians and professions in science and engineering, intermediate level
35 - Information and communication technology technicians

But this doesn't make it totally clear to me, although various websites claim that "computer consulting" and "web development" qualify.

It also says:
Workers included in the above-mentioned professional activities must have at least level 4 of qualification of the European Qualifications Framework or level 35 of the International Standard Classification of Education or have five years of duly proven professional experience.

I can't figure out exactly what US education level is equivalent to EQF 4 / ISCED 35. I'm also curious about what "duly proven" entails.

The second question has to do with taxation and business structure.
What I want to clarify is whether I would be able to form a Portuguese single member limited liability company, which seems to exist as a pass-through entity for taxation similar to a US LLC, and still a.) qualify for the 20% NHR income tax treatment, b.) still pay around 21% in social security, and c.) still qualify for the social security tax cap of around (EUR)14K/yr?

(Apparently the Portuguese equivalent of a C corp imposes social security taxes on board members and directors on all of their income with no cap.)

The third question seems pretty straightforward but I haven't been able to find a clear answer: All of my clients are in the US, so would I have to pay VAT on these contracts?

Thanks for any information.