I never said that Giggs isn't the right man or that Van Gaal doesn't need a number 2. Infact I think it'll be a good match. Van Gaal may be obstinate and fanatical but he's a great teacher and mentor (You only need to look at some of his former pupils - Jose Mourinho, Pep Guardiola, Frank De Boer, Frank Rijkaard) and he'll impart invaluable tactical knowledge to Giggsy if Ryan is willing to learn and is flexible. That said Van Gaal will not take any advice on playing style, tactics, team selection etc.
Giggsy can be helpful in bringing the academy/ reserve boys to Van Gaal's attention, liaison with the players, and a million other miscellaneous things. But the day Van Gaal detects any interference in footballing matters on the pitch, it'll be the end of their relationship. Van Gaal will learn in detail about United and the league, but in his own way. He won't take advice, unless he seeks it personally in confidence.
Football is the same everywhere, irrespective of league. It's all about implementation. If Pellegrini, Jose, Benitez, Ancelotti can be successful in the Premier League, there's no reason why Van Gaal - one of the greatest tacticians ever - won't go on to do the same.