Does it matter what my account name is?
How many characters can I have?
In Breach you have a single hero character that can select different classes of combat for different missions. Your character learns and grows across different disciplines, but you'll have a single Hero and a single Veil Demon. The name of your account will be the name of your character.
When you go into battle as a Pyromancer you'll have the same name, appearance and gender as when you go into battle as a Lich.