Yes: Adu was called to the US camp by Bruce but so were a number of players and Bruce said that they will have to earn their spots.
Unlike Messi and the others who moved to Europe at an early age, there are some specific FIFA Laws  (and EU Labor laws) that prohibit minors moving to Europe before a certain age. I cannot remember the exact specification but I remember Adu did not meet any of the required loopholes so he has to wait until he is 18. Bear in mind that English laws regulating the movement of child labor tends to be a bit more strict than say Spain or Holland.
Hell NO!!! Freddie cannot make the Ghana squad. This is arguably the best African team in this year's Cup. Essien, Muntari (Udinese) Appiah (formerly of Juventus) and are the three stalwarts if that team's midfield. These players are experienced, strong fast skillful and physically imposing... Feddie cannot start with this team... Cannot!!!
Nike has too much invested in Freddie for him to play for Ghana. he is one of the USSF poster boys, plus the financial incentives for him playing for the USA are too significant to ignore.
Freddie's progress has been hampered by DC United. He would have been much further ahead at a bigh European club... the quality of training is just not the same and cannot be compared at all.
When looking at a young player like Freddie, all you want to see is whether or not he has a developed sense of game awareness, foresight, technique and skill. He is not overrated but the MLS is not a skill driven league, it thrives on physicality and muscle bound play, and in many ways Freddie is made to look mediocre by his teammates. When his physique catches up to the other excellent aspects of his game, he will blossom.
PS: look at Beasley before and look at the improvement since his arrival at PSV... Freddie would do well to follow his example.