Sounds right, though I've never had a problem either finding or organizing a minyan there at any given visit at any time.
Is the Ohel a minyan factory like 770?
No
Often for mincha and mariv ppl gather to make a minyan. But there is no guarantee there will be a minyan other than the kavua times.
Right. So it's not a minyan factory. Lesson learned
What's their schedule?
Any information on JFK shul is there usually minyan scharis before 11 am Elal flights? https://internationalsynagogue.org