To be "for" or "against"
¡Hola a todos!

I'd like to know, how do you say, for example:

1. "Are you for or against changing the name of the company?"

2. "Are you (going) for Real Madrid or Atletico?"

¡Gracias a todo!

Question

To be "for" or "against"
¡Hola a todos!

I'd like to know, how do you say, for example:

1. "Are you for or against changing the name of the company?"

2. "Are you (going) for Real Madrid or Atletico?"

¡Gracias a todo!

Answer

1. ¿Estás a favor o en contra de cambiar el nombre de la empresa?

be for = estar a favor
be against = estar en contra

It's a bit more difficult with the second one and I'm sure it would depend a lot on local expressions.

The most usual expression I can think of here in Spain could be 
¿Eres del Real Madrid o del Atlético? (if you are always a fan) 
or 
¿Vas con el Madrid o con el Atlético? (who's your favourite in this particular match)

Sorry for the long explanation! :)