Easy way of posting for multiple authors / auto-categorie for every author

Hello everybody,

1) I’m looking for a way to allow 10 authors to write in my blog – but these poeple are really just able to type in some text.
So what I want is a button / link “Write an article”, a simple login-form and a textfield to write (maybe with editor). I don’t want the authors to login to the admin-panel.

I want the articles of every single author in a categorie – automatic…
Is there a way to do this?

THX a lot,
Bruz