Recent experience on LA531 JFK-LIM-SCL in J
 

1. First and foremost, everyone has to get off at LIM, re-clear security (no need for border control) before continuing to SCL. I don't think this mentioned anywhere in my booking. By the way, LIM has plenty priority pass restaurants and lounges. Business class passengers could also use the Sumaq lounge.
2. Departing JFK at T4, you can use the delta lounge if flying in J. Food is not bad at all and I would totally eat the dinner at lounge and skip the dinner on board.
3. No menu on board and the breakfast is a bit under underwhelming.
4. AFAIK, Latam uses the old-config 788 on this route. It's a bit awkward if you are in the window seat and need to climb out. Seats are comfortable for sleeping.