I speak Esperanto and I am quite active in the movement and write for the Esperanto Wikipedia. In 2011 I had quite a cool trip to an Esperanto Youth Congress in Kijiv. But it's hard to talk about it because most people see it as a failed project from the early 1900s, not as a modern subculture.
That's interesting! A few friends of mine and I tried to get a hold of it during the last school year. But we were greatly annoyed that there was no good free/open source resource in our language. Everything that could be good material was basically "Pay for the course" or just buy the book for 50€. That demotivated us quite a bit.
I get why you would like to make a buck for your work and yes learning languages in groups is more fun but besides badly formatted vocab sheets there was no resource that was a proper introduction to the language.
That's not an issue anymore. There is an Duolingo course, tons of Anki vocabulary decks, the app Drops supports Esperanto and the website lernu.net has a pretty good free course to learn Esperanto grammar.
I couldn't find the name of the story. 99% sure the author is Howard Waldrop. In WW1 a group of soldiers sneak into No Man's Land and create an underground nation where all men speak Esperanto.
Mi volas konvinki mian edzinon al lerni kun mi. Mi pensas ke se mi povas praktiki kun alian homon, mia gramatiko kaj vortfarado pliboniĝus. Sed ŝi ne volas.