First of all - thx for the welcome
I do not think that this deal has written van Gaal all over it. Or a least I hope so. Van Gaal implemented the possession-style in Munich; that is right.
So you are kind of right that both coaches are conceptional.
But besides that there are no similarities between these two coaches. It is more than obvious that Pep has another style to deal with his team. Van Gaal is a one man show, which does not really work well in big clubs like Bayern (or Barca), where the headcoach is the leader of a team of coaches, scouts and so on.
I also do not think that Pep is a one dimensional coach. Bayern will never be a second version of Barca. It will be interesting to see how Pep will transform his philosophy for the players he going to work with. In clubs like Bayern time for development is always short and you´re right arguing that the likes of Hoeness and Rummenigge are kind of impatient if there is no success.
I don´t know if they´ll give him the time, but he might have a good partner in Sammer to shield him when needed.