to answer your questions:
1. yes, people can change between those ages...but that doesn't mean he didn't know what he was doing at 15 nor excuse it...he knew what those words meant and what he was singing about...
2. no, because being there is plenty of info out there to disprove racist thinking, but people that are racist ignore it....they don't begin to change how they think until something happens in their life that goes against everything they think/believe about others...it takes life experiences to change racism, not just picking up a book or looking at videos that show you how words hurt...
3. I know what he thinks of blacks by the way he portrays himself...he's perpetrating a lot of stereotypes about blacks in his mannerisms, talk, walk, dress, behavior, etc...he's trying to show he's down by emulating what he thinks it means to be black...we see that shyt all the time with a lot of white entertainers that try to show they are down....another recent example: miley cyrus and her 'urban' image....
...anyway, what the fukk happened that has you talking like this and not like the cat I was riding with during the sterling shyt?....you were going hard with the inherently shyt then, but not so much now....if you fukks with beiber and that's why you riding for him, that's cool...that's all you got to say....but don't tell me you've given up the cause...that's not what we need....we need more to wake up.....
edit: in regards to bieber, I didn't give a fukk about him before this, damn sure wont give a fukk about him after this....not surprised music entertainers are coming to his defense...they see money in him, and that's more important than being a black man/woman to a lot of them...hell, to a lot of people period, the clipper players and coaches showed us that as well with the sterling shyt....anyway, hopefully just like the sterling shyt, this is a wake up call to those brothas/sistas that needed it to realize the only people that care about us is us....