Multiple characters at once?

[SnowVix]

The game will kick out one of you if you both try logging into the same account.

Also, I'm not sure but I think if you have a PS4 account you can't use that to log in to the PC version? SOMEONE PLEASE TELL ME I'M WRONG!

you need to buy each expansion on each console, but you can use both on the same account. all 3 if you want to count Mac version