Getting from Munich airport to Salzburg Hauptbahnhof?

Take the S8 Sbahn to the Munich Hbh, then book the next train to Salzburg. No need to book in advance for any regional train. See the DB website for details:

https://int.bahn.de/en

Thanks. I was looking at the DB website. Some routes take me through München Ost rather than München Hbf. Is it better to go through one or other?

after the early morning restrictions (not before 9am M-F) the whole family goes on one Bayern Ticket. 2nd class, regional trains only throughout Bavaria and to and from Salzburg. All the trains you can eat in one day.

5's and under are free, up to three 6-14's are included for free with the adult. 14 + are full adults on the ticket.

The Bayern Ticket = Bavaria Ticket in English.

https://int.bahn.de/en/offers/regional/regional-day-ticket-bavaria

be sure on that ticket not to get the IC services. Regional only.

Ost is a perfectly good change point. Just know that folks who boarded at the Hbf will already be on board. Ost means east.

There are 2 s-bahns from the airport, one clockwise in the middle of town, one counter clockwise. If you are on the one which gets to Ost first, perfectly fine to change there.

Some routes take me through München Ost rather than München Hbf. Is it better to go through one or other?

Munich Ost is between Munich Hbf and Salzburg, so it is a little bit of a shortcut. But it all depends on when you are ready to depart. The transfer process is also simpler at Munich Ost as it just a transfer between platforms, whereas at Hbf, you arrive at the underground S-Bahn station, make your way upstairs, then locate the new platforms, which generally at the far end from the S-Bahn station and set back from the rest of the main platforms.

If it were my choice, I'd choose to change at Ost (I have twice). You do have a short boarding time at Ost, and people from the Hbf already have seats, but that has never been a problem for me. Maybe in high travel times? Otherwise, it's just faster.

As Sam mentions, it's a much longer walk to change at the Hbf. Trains to Salzburg leave from the "Holzkirchen Flügelbahnhof", a "wing" station added to the south side of the ground level tracks in the Hbf, and a bit of a walk back from the platform that connects tracks 11-26 in the main shed.

When you go from MUC to Salzburg, make sure you take the S8. It will say to "Herrsching" or "Weßling", but it stops sooner at the Ostbahnhof than does the S1, which will probably say "Leuchtingbergring".