Are you kidding me? Of course he's a liberal. His entire show is a satire of a punditry show such as the O'Reilly Factor, as is extraordinarily obvious by his idiotic character and intentionally clear logical flaws. Wikipedia has separate articles for Colbert's character and his actual person.
Yes. Smoking pot may not be a good idea, but it's no more harmful than alcohol or cigarettes, and does not harm anyone who doesn't choose to take it up. Especially with our current budget restrictions, we can't afford to save people from their own stupid decisions.
We're not really there yet. The fact that we have a black president doesn't mean that most blacks or any other minority have the same opportunities as whites. In reality, a large percentage of the population still holds prejudices, whether conscious or subconscious, about other races.