Well you picked some pretty good parts for dirt jumping. The main thing you want to keep in mind when buying parts to ride dirt is that you may take some really hard landings so strengh is very important. Weight really depends on the rider if your big dont worry about it. But if your a strict dirt rider the best way to save weight is no pegs and no front brakes just have the bare nessecities on your bike to go and stop. The best advice I can give you is just ride as hard as you want with what you have ... and my moto is break it and replace it with something better so if that happens then just get something stronger. Its almost fool proof way to get your bike perfect.