Note bus A2 also goes to Sagrera interchange at peak hours, which is more useful as it has more connections to Metro lines. Those buses are marked green at the ...
It is Zone 4 for Rodalies only tickets. For ATM tickets is Zone 3.
Lots of things to consider: checking luggage? Flying in or out Schengen?
For your tranquility, use N16, N17 and N18 night bus services.
Take a taxi and don't worry. Pretty easy.
It is also good to fill out this form, it helps make things easier for Aena: https://wwwssl.aena.es/pmr/inicio?lang=en
Any train on Platform 2 at Plaça Catalunya Rodalies station will work. They run every 3-5 min.
They are free of charge with your AVE ticket, using the Combinado...
If you are changing systems: eg Metro to Rodalies, then you will revalidate the ticket, as you will find gates that won't open unless you validate.
You can't book commuter trains, the same way you wouldn't prebook a tube train. Just turn up and go, it's fast: rodalies.gencat.cat
If taking the train, look at. rodalies.gencat.cat for accessibility
The best for you might be getting bus 24 or 92. It is justified to use them in this case. Ah, don't hesitate to ask for a seat in the bus, it is more than justi...