Qualifications in short:
10 matches - 10 wins. However, it was far from easy and some of those matches were very complicated (you could say that the NT had a lot of luck in some of them).
1st match against Bosnia - Villa's goal was offside
1st match against Belgium - a nightmare, had it not been for Puyol, the result would've been different
1st match against Turkey - Piqué's goal was the only thing that separated the two teams
2nd match against Turkey - a win thanks to a late goal, dull game and we were 1-0 down (however, shoed great spirit by coming back)
Del Bosque gave a chance to many players like Bojan, Negredo, Mata, Capel, Busquets etc. But for me the biggest revalation was Piqué. He didn't even need time to adapt to the NT. It's like he's always been there. He has a guaranteed place in the starting 11 already.
Torres was very disappointing, he didn't score a single goal and Del Bosque should think about replacing him with Cesc who took advantage of every chance he was given.
It'll be very important that Senna is on form in time for the WC. His only replacement is Busquets who is still a young player who has a lot to learn. Capdevila is in a similar situation as Senna, another player who doesn't have a clear replacement, though Del Bosque recently started calling up Monreal on Camacho's advice.
Del Bosque will have a though job to pick the 23 players for the WC.