Welcome to MusicBrainz!
Here's the guideline for it:
Performance names and legal names
Generally, use the name the artist mainly performs under as the artist name. Alternative names, including any legal names and name variations, should generally be entered as aliases, and can be used in artist credits and relationship credits when appropriate.
In some cases, a person (or, more rarely, a group) can perform under multiple names that they actually consider different projects, and not just alternative names. In that case, you should add each artist separately. If they're a person, a separate legal name artist should be added, and linked to all performance names with the is person ("performs as") relationship. In this case, do not add legal name aliases to the performance names. For groups, just link each group to their members.
There are some examples on the wiki page:
For your last question, you mean listing all releases combined ? That's a good one. I don't know!