Metal cabin spray paint project

Submitted to Product Chat

Hi - this is  a first for me! - could you advise on any of these questions:

1.  what spray paint range would you recommend?

2.  I have scrapped the surface of paint, down to metal, some say a primer is not necessary is this true?

3.  To do details can one paint on top of spray paint with small brushes - if so what type of paint can be

Thank you 
Hali Holly
United Kingdom