How to customize the login element of upfront

Hi there,
I am trying to customize the login element of Upfront to fit my design.
I have managed to customize the form text and the field text layout.
Also I have modified the login button.
I have several questions:
- How can I remove the link: "Register"
- How can I change the background color of the main box?
- How can I remove the border of the main box?
- How can I customize the font styling of the closed login link when I am logged in?
- How can I customize the font styling of the closed login link when I am logged out?
Thanks for your help.
All the best
Renaud