First two you new guys. Do yourself a huge favor. Go buy and read this book.
http://www.howtobrew.com/
I read it about 5 years after I started brewing out of a starter kit like you're doing, and I wish someone would of directed it to me after my first beer. Read through it with a highlighter, and don't focus on mastering the small formulas. Your initial read will give you insight, answer so many simple questions that at the moment, understandably, seem important. Once you figure your process out a little better, and get more experience, re-read it or re-read the detailed stuff that you now have more experience to make sense of it.
Secondly, as mentioned, airlocks are not the end all be all. In my opinion, Krausen (foamy head) is a much better indication of fermentation. I just made an amber that bubble for 2 days and then stopped entirely, but the krausen remained for 6 more days. My FG numbers were right on the money.
Third, this is my opinion, don't take hydrometer readings from the fermenter. Take a sample and take the reading from that.
Finally, fermentation is done when it is done. I my primaries go for as long as they're showing activity. Once they stop, I give them an additional 2-3 days to clean up as others mentioned.
Secondary is unnecessary unless you're doing something additional to the beer that you don't want mixed in with the residuals from the primary. I'm going to take a 10gal porter that's split in two fermenters and put one in a keg and one in a secondary this afternoon. The secondary will get the vanilla and coconut additions. However, it's not for the purpose of fermentation, it'll only sit in there for a few days and then go into a keg as well. Or if you're using the secondary for it's actual purpose. Read this article.
Secondary Fermentation
Seriously, read the book, it'll answer a lot of your questions you haven't even thought to ask.