Really? I'm not so sure about this. Maybe a membership card (which you don't need to be a Dutch resident for necessarily) for certain games, for example, Feyenoord. With these games you need to bring ID alongside the membership card which is a prevention against crowd trouble.
It should be a great game, I hope you it and Eindhoven! Excelsior are the smallest club from Rotterdam so they will probably only be around 100-150ish.
It depends on the game. Getting away tickets is especially difficult for some teams such as ADO, where although it may not be sold out, you have to be a member and take the coach to away games. Home tickets can usually be bought on resale sites if it is sold out.
Not sure why PSV is so...