I know there are parents here with kids in Galaxy or LAFC academies so they'll be able to add the best insights... but I can answer these Q's based on talking with some of those parents + doing my own research...
1. Yes, those 3 are the only academies... except SD FC academy isn't open yet... their academy is planning on opening doors Fall 2025
2. yes, fully funded, all gear, tournaments, travel, league, games, nutritionist... you pay nothing
3. includes academics in different forms. In younger ages I believe with FC and Galaxy, you figure out school on your own and then starting like U15, you do fully online school on site.
Here's the info on Galaxy academic program -
https://www.lagalaxy.com/academy/school/about
Previously they used Connections Academy (
https://www.connectionsacademy.com/) but I think they're now using CA Online Public Schools (
https://californiaops.org/). They're both online home school options, with tutors on hand to help navigate the academic side of things. I have an educator friend who worked with the academies a bit.
For SD, San Diego FC will become the first Major League Soccer club to offer a privately operated school combined with a residential football academy.
SD model is truly special. First ever residential + a full school. I think it'll be the gold standard going forward with MLS academies but we will see how quickly the other academies follow or at all.
4. Only SD is onsite and only one in the US. You have comparable programs like Barca Residential Program in AZ or IMG Academy in FL but as far as MLS academies go, I believe SD is the one and only. Oh and SD FC is free. Barca Residential is like $80,000 a year or something. IMG too LOL.
5. Some younger teams play EA like LAFC has a U12 team that plays in EA right now. But Galaxy's youngest team is a U13 and plays in MLS Next. And older teams all play MLS Next. Generally most MLS academies seem to start at U13 MLS Next level but I assume some like LAFC has younger teams in EA (cause there is no MLS Next in U12). Then in U15 and U17 they have regular MLS Next, Flex - I think this thread explains that a bit
https://socalsoccer.com/threads/mls-next-league-vs-flex.20782/
I think the fact that you can play against MLS academies is why there's a perception MLS Next is the highest league on the boys' side - rightly or wrongly. You ball out against them in league play or tourney and you could get recruited. It's happened at my kid's current club.