As u/sp222222 mentioned, Euchre is more of a "feel" game, so there often isn't a right or wrong answer. If there is a right or wrong answer it often depends on what is in the other players' hands, and which player has which cards, which is impossible for you to know with any certainty.
That being said, I recently created a Euchre game for Android, and it includes an option to show suggestions on which card to play. https://play.google.com/store/apps/details?id=com.fifteen15studios.euchre
My computer players (and these suggestions) are better than any I have seen in any other app on the Play Store, and the lack of intelligent players in other apps was one of my main motivations for finally making this available on Android. That being said, I'm always looking to improve this logic, as I'm sure it's still not flawless (even if it is better than the competitors.)
I grew up in northern Indiana and we played Euchre very much. You can usually rustle up 4 people who play at any given family event or large gathering.
When I was in middle and high school it was not uncommon to have a lunch table or two where some kids would play a game. This was in the mid-90s and I'm 31 now. I can't really speak to demographics younger than myself, but for me it was not seen as an old person's game.
There are frequently Euchre tournaments/nights at bars around larger cities that would attract a lot of people in their 20s. Depending on where you live, it may be a different scene.
For a book recommendation that goes beyond the simple "how-to", I would suggest The Columbus Book of Euchre.
This is actually the only "farmer's hand" rule I ever play with. It's such a rare occurrence that I think I've only seen it actually occur like 5 times or less in real life (and I used to play A LOT of euchre in college.)
I did implement this as an option in my app:
https://play.google.com/store/apps/details?id=com.fifteen15studios.euchre
Note: All farmer's hand / redeal options are off by default. You'll have to enable it to play with that rule.
You might like The Columbus Book of Euchre.
It's a little bit weird, but it does talk about a ton of the terms.