Why Does Ichigo look different after he gets his soul reaper powers back?
I assume that it's because he retrieved his powers with the help of a lot of Shinigami who gave a part of their powers to create the sword Rukia used to reawaken him. But I'm not really sure it is the only reason actually.

And yes, Zangetsu is still within him, just keep forward into the manga, there is a lot to see about that subject.