So to say something like 'I want to be a writer', would it be я хочу письменник?
Я хочу бути (стати) письменником
You can omit to be (бути) in Present (where it has a form of є), but not other forms. And to be someone/something requires Instrumental
Why isn't there a dash between я and письменник? Up until now there was always a dash in place where a form of "to be" was omitted.
You need a dash between a noun and a noun, but not between a pronoun and a noun. However, you may include it for emphasis