1. What would you say is the most defining attribute of this discourse community aside from the stated ideology (that the earth is flat)? What can you say is the most vibrant denominator in the followers of tfes?
For full disclosure, I have only posted here for a short time, so my opinions are based over a short time frame, and are also influenced by various videos I have seen on YouTube and the comments posted there. In my mind I am answering in regards to believers in FET in general, as a group that also includes the proponents on this specific site.
I think the biggest common attribute is a mistrust of government and scientific authorities, a contrary nature one that borders on a religious zeal. If a person sees something that they don't understand or doesn't fit with what they can sense, the normal inclination is question it and look for an answer from someone capable of explaining it. The FET believers have a mistrust that leads them to become convinced that anything that conflicts with their senses or understanding can only be driven by a mass conspiracy to fool the people. I suspect there is a weird sense of pride and purpose they lull themselves into by being in the tiny group to not fall for the evil conspiracy.
A secondary attribute I see is in how they view evidence. NASA can release tens of thousands of hours of video over decades. A FET believer can spot for one second a spec of debris floating in an unexpected direction (proves it was filmed in a studio) or the corner of a t-short pointing out (proves the astronauts were on wire supports) and then become absolutely convinced that they have caught NASA's lie. Therefore this proves everything NASA ever did was fake, all part of the conspiracy.
On the other hand, they look at one drawing made by an FET believer and accept the whole of all FET without questioning anything, even if it conflicts with what they see with their eyes. Just look at those animations they show with the sun and moon revolving around the north pole. Do the phases of the moon match what you see if you look up? Of course not, but FET believers believe 100% of FET with 0% skepticism, the complete opposite of their approach to everything else. Everything not FET is to have doubt thrown upon it, sometime just to derail conversations I think. I actually saw post from Tom Bishop (A Zetetic Council Member) where he remanded someone to prove that GPS works. Seriously?
2. How did you first become involved with the Flat Earth Society?
For me it started with the recent solar eclipse. I was looking at videos online and started seeing flat Earth videos in the YouTube suggestions. At first I didn't think there were actually people that believed in flat Earth, but I guess there are. I started making some comments on the videos trying to explain things. It was apparent that some people refused to accept reality. But I still did some posting hoping to help those who were open minded are were really looking for information.
3. What actions have you taken so far (if any) to further the agenda of tfes?
I do not wish to further their agenda, quite the opposite. But to be fair, I came to this site to seek some specific information that I could validate through basic observation against the accepted RET. Hoping to complete that soon.
4. What is your commitment level to this ideal? Are you one hundred percent sure of your path and a ferocious advocate or a curious individual interested in different ideas?
I firmly believe that we live on a sphere orbiting the sun. It would take substantial and concrete evidence to convince me otherwise. I studied astronomy for years and considered it as a possible career until my early college years. In years of reading books and magazines, years of watching and studying both space and the space program, hundreds of nights in my front yard with a telescope, I never saw anything that conflicted with round Earth theory.