Quora is global, so relative to the US it has a 'left bias', even though it is mostly more conservative than the global audience.
Pete,
The internet is doing that in general, it's not anything particular to quora.
I'd argue that the 'internet as a whole' really doesn't act in that way. If you write something interesting on Quora there is a reasonable chance of it turning up on Fortune, Huffington Post, and other widely read publications. There are only a few places on the net you can post and have any likelihood of greater audience. Also there are a large number of influential people that hang out at Quora. Both posting and reading to a degree not found anywhere else on the net but twitter (and twitter is almost completely inconsequential in its content).
DW,
you can ask up to 15 different people to answer (suggestions for who to ask are given based on those who have answered and received lots of upvotes in the topic areas that are associated with your question, and based on who you follow, who follows you, and who you upvote). As long as it is a well written/interesting question, there is a good chance someone you ask to answer will answer.
JoshuaD,
in addition they regularly promote material to other readers, so well written stuff gets more viewers.
Upvoted material by people you follow is more likely to end up in your feed, and material by people you follow is more likely to end up in your feed (unfortunately their algorithm is a bit imbalanced, and you can end up with your feed flooded with writings mostly by one or two authors)
Followers is also an important aspect in general.