1.Is it possible to extend the reach of my piston?
2.Is their a way to hide my Redstone trails?
3. Can I connect multiple switches to the same source?(e.g. 2 levers attached to one piston on either side of my secret opening?)
1.) No, but it will push (I believe) 12 blocks away from itself. A sticky piston will only pull the first one back, though.
2.) Not really, except by placing a block in the space above your red stone.
3.) I think so, yes. I don't see why not...? I could be wrong on that one.