As for Handel's Hallelujah, being a fan of classical music, I am sure that Pope Benedict is a great fan. This does not mean that is should be sung at a liturgy. At a special concert in praise of God, by all means!
his statement about Protestants not being real Christians.
The Pope never said that Protestants were not real Christians, but rather that their ecclesial gatherings were not true churches. This flows from the Catholic belief that a church is a divine institution based upon Apostolic succession of Holy Orders and centered around the Eucharist (neither of which most Protestants claim they have). It is a question of Sacramental theology. As for being a real Christian, this comes from Baptism. Provided that the proper matter and form are used, the Catholic Church does indeed recognize that baptized Protestants are real Christians.