1.) Yes.
2.) I say close to about 60 to 75HP over stock with intake and exhaust. See this thread when we got dyno'd (Mine with SC and Johnnyapollo's with same mods as me only minus the SC and cooler plugs).. http://www.vehicross.info/forums/sho...highlight=Dyno
3.) Have had no problems with the SC other than one leak on the cone.
4.) Intake, Some sorta of exhaust I have duals now gained almost 9.5HP going to the better flowing exhaust (Cats bigger pipes etc), one step cooler spark plugs, shift kit... Mine is going back in the shop for more tuning this week, will let you know if I squeeze more HP from the other mods that are going on. My last dyno was 225.36 to the wheels. All this other crap can be $$$$. But you gotta pay to play.
5.) Yes should have came this way from the factory.