(Bolding is mine for emphasis.)
Actually, I’ve seen very little evidence that the Amish eschew wealth. They don’t buy bling or Porsches, but they acquire money in a very deliberate and organized fashion. Business skills are no sin to the Amish I do business with. My impression (though I haven’t asked them) is that they equate actual poverty with laziness.
There actually are Amish websites. Some are joke/parody sites, but there are genuine, serious Amish websites, hosted, posted, and maintained on-line by Mennonite neighbors with computer access.
I live down the road from a fairly large Amish community. Amish don’t mix much with outsiders - don’t get me wrong, they are curteous and polite and will make idle conversation and are happy to do business with you, but anything more than that is pretty unusual.
The Amish are primarially of Germanic descent, and among themselves speak a dialect of German. I’ve yet to meet one that wasn’t also completely fluent and bilingual in American English, too. However, they have had converts from other groups over the centuries so you’ll find the occassional non-German surname.
Unlike the usual Hollywood portrayal they aren’t ignorant bumpkins. Sure, they’re not familiar with some aspects of mainstream culture but they are very aware there is another world outside their communities. Amish are perfectly capable of using phones, for example, they just choose not to. Thanks to their custom of letting teens run a little “wild” - that is, they look the other way as their young adults look at the outside world, they even have a formal term for it I can’t recall off the top of my head - quite a few Amish know how to drive and may have held valid driver’s licenses at one time in their youth.
They’re big on the idea you have to, at some point, choose their lifestyle/beliefs. It’s only after you make that choice, as an adult, that you can be baptised into their faith as a full member. If you choose to leave for the wider world before you’re baptised (and about one quarter of their children make this choice) then you can stay on good terms with your family. Such people might refer to themselves of “Amish descent”, or “former Amish”, or “from an Amish family”, or even “Amish” but with the qualification they aren’t members of an Amish church. Ethinically, they’re usually considered German. If you choose baptism and the Amish church, THEN you have to toe the line or face being ostracized and shunned.
The Amish “rite of passage” in the outside (“English”) world is called Rumspringa. AFAIK your description of it, and of the importance of the choices made afterwards, is spot-on.