Are there discount tickets for the rest of my route or should I just buy them when I get to the city?
As was already stated:
Prague to Salzburg
Purchase discounted ticket in advance here -
https://eshop.cd.cz/international/search_cd-obb.aspxWhile Warsaw to Krakow; Krakow to Prague; Warsaw to Olsztyn legs can be bought already at the station before departure.