A great place to learn about this stuff is on IRC:
FreeNode (this network is popular among many developers)
You'll need an IRC client (there are many to choose from), or you can use the web-based chat at http://webchat.freenode.net/ if you prefer. The #Linux and #Ubuntu channels are very popular there, and would probably be really good places to get started -- you can learn a lot just from watching what the thousands of people ask about on this helpful network.
SuperUser.com has a Chat system as well, which I believe has a pretty busy Ubuntu channel (they call them "rooms" rather than "channels").
Also, take a look at the long list of [mostly] well-known Linux distributions, and at least try a few of them before getting your heart set on one in particular:
Resources - Operating Systems - Linux distributions
Each distribution of Linux has its advantages, and also many differences (some are more noticeable than others). Depending on your needs, one distribution that meets all your criteria may not be suitable for someone else. (It sure is nice to have all these choices!)