Aluminum typically snaps instead of breaking. It is actually a much stiffer metal than steel is when made for bikes because it is made thicker. With steel, there is some flex in the frame (a tiny, tiny bit) that helps it last longer. With aluminum, there is less flex in the frame, so the metal has to absorb the impact of everything you throw at it. (not including grinds) So, aluminum will wear out after a certain amount of time no matter what. If you have a steel frame, then if you aren't grinding it, the frame could last you ten times as long as an aluminum frame. Well, it obviously depends on how hard you are on the bike, but it is possible to get 5-10 years out of a steel frame if it isn't something you grind on.

For your dropout, you can take a large adjustable wrench and lock it around the dropout and VERY carefully bend it out slightly. You can also just have your dad or a friend help you pull the back end of your bike open slightly to allow you to pull the rear wheel out. If your dropout is bent around the axle, like a C with the axle in the middle, then you want to pull out a hammer or a large tube of metal that you can wrap around the dropout and bend it down to open it up. It is very damaging to your dropouts to not protect them from that kind of abuse, and there is stuff you should look at to protect them. It may cost you 20 bucks... but a new frame costs a lot more than that.