Also a good practice I have learned is to time out you return to ship ratio and when new game comes out, clear the Q keep that new game in first and return the game you have before the release date so on release day you will be a first shipper.
This method is great, it has worked for me many times. I will return my games on the Tuesday before the new game is released the following Tuesday and just wait to see if it lands. 90% of the time it will ship Monday night the following week.
You cannot trade games anymore, and even when you could you would only be able to get credit for a game, it was not a 1 for 1 trade.
You will need to put Uncharted 3 on your Q and wait for it to ship once you have no games currently out.
When you cancel your membership it would be best to send back the games right away. But as long as you clear your Q and send the game back before the billing period the cancellation should stick and you can then do what you need to do.
That will depend on the availability of the game, if you receive a notification saying we have shipped out X Game than that means the game has shipped.
Typically what happens is Gamefly will receive a a returned game, then it will process your Q and figure out what they have available. Once the available title is selected the game will ship.
For me once they receive a game I will get a notification that day of a new game that has shipped or the next day. I have not seen it exceed 2 days though.