Daisy asked about the IJ and Y… The rule is that IJ is a vowel combination and not a separate letter, the latter being the case for Y. Hence, words starting with ‘ij’ are alphabetized between ‘ig’ and ‘ik’ (I don’t think Dutch words can start with ‘ih’ or ‘ii’).
However, to make life easy for us Dutch humans, you will find that the IJ is sometimes alphabetically listed under Y, as it is the case in for example the (paper) phonebook.
Also in modern day SMS texting, lazy Dutch might write ‘y’ for ‘ij’.
When a word starts with ‘ij’ and is a name or is at the beginning of the sentence, the entire ‘ij’ combination is capitalized. This contradicts its status as a ‘non-letter’, however, this is the rule (see for example DWOTD 23. IJsbeer).
The ‘ij’ originated as a prolonged ‘i’, which was written as ‘ii’ in old Dutch (much like we write ‘oo’ and ‘ee’ now for example). As the ‘i’ was often written without the dot, the ‘ii’ combination could be mistaken for a ‘u’. This is why the second ‘i’ got a ‘j’ shape (without the dot), which later became a ‘j’.
Quite often you will encounter Dutch names that only differ in the use of ‘y’ or ‘ij’. This originated because both the prolonged ‘ii’ (‘ij’) and the ‘y’ sounded the same.
Hope this clarifies it!