i made a mistake by not doing what i am about to tell you right now. get a good first stage look at apex or scubapro, after that buy two of the same second stages. put your primary on a 5-7 foot hose, and the other one on a regular hose. put the secondary one on a necklace for you incase your buddy has an ooa situation. this will have less failure points and the intergrated systems brake often and are unreliable. plus if you ever move to doubles you can just buy another first stage.
At 14 years of age, it would be better for you to listen than to hand out advice.