Artist, artists, artistsort, albumartistsort

[ohrenkino]

@Alfie_Solomon84

Also, where can I read all the available fields in MP3TAG?

To see the fields that are already in a file, see the extended tags dialogue (Alt-T).
To get a list of all supported fields see the help:

Tag Field Mappings – Mp3tag Documentation

In respect to the fields that you mentioned:
ARTISTS is a user-defined field and will only be shown by players that support such fields.
Even though it is possible to create multi-value fields with MP3tag (several fields with the same name), such fields find hardly any support in players.

So the answer to 3: I don't know this depends on the player and its features.
The purpose of the sort fields is mainly to group names together that may vary like "Beatles" and "The Beatles". And as the purpose is grouping, it would be counterproductive to have several sort criteria.
On the problem of separation of artists, please see also this thread:

Should I use ";" or "\\" or "-" as a separator?

Ohrenkino, you raise a good point with the "/". I do use the " / " and, as I recall, I believe the reason why I added the spaces is for bands like AC/DC. I think I went with the "/" because some programs used it as a separator, and WMP may have been the one that convinced me, even if I do not use it as of yet. In the CD Ripper from dBpoweramp you indicate multiples with ; which means that the program writes multiple fields but the ; itself is not written into the metadata, it's just an indica…