Question regarding policing of football matches

I’m not a Bolton fan (infact I rarely watch football) but I was horrified by the pictures of the events at the Atletico Madrid - Bolton game. 17 Bolton fans in hospital, from injuries caused by the police.

BBC Sport & Guardian Sport
Will the events of the game have any repercussions for the Spanish FA?

How do the levels of match associated violence compare between the major European leagues?

What are the different approaches to policing? Is there one approach that is considered the most effective?