Do spanish controllers know anything about that?
Nope.
Are you looking for someone to help you for your holiday,shift,days off..
Nope, although that would be nice
Does spanish union know something about the agreement between the two providers?
Not that I know
I want to know any useful information
I can only tell you about Barcelona
1670 hours per year, up to 200 hours a month, 5/3 days work/off ( 6/2 in the summer), 45 days vacation (maximum 15 days between June and September ), around 5000 euro net per month, and, oh yeah, everybody hates you.....
Any doubt, don't hesitate to ask
Regards