Refactoring some critical parts

Refactoring some critical parts

Critical issue fixed here: after recent refactorings, I called
get_users_with_capability() inside the loop in another loop! (oops :-)
This was used in my very first code using the renderers. I have learnt
I should follow the core approach (as suggested by Tim) to prepare a
data object and pass it to the renderer. The fact the renderer called
a workshop method indicated something was really wrong...

WIP