Looks like you have a VERY nice start to your Reef!! With everything you have I seen no reason why you couldn't keep SPS (Lacking tank maturity, wasn't stopped people before) I would definetly start out with softies and "easier" corals.
Curious why you rebuilt the stand? The halides will do just fine.
As for your test kits and suppliments make sure you find the expiry so they arn't leading you in the wrong direction.
As for the Ratio / LF to Dead rock there isn't any amount you need, The more you use the less of a cycle you will see. I would do 20% but take a look on canreef in your area maybe you'll be able to pick up some for a cheaper price. 3lbs/ pound isn't uncommon.
Good luck, you are definetly in the right place for information and to point a finger in the right direction.
EDIT: ======= As for the silicone - I would go to your LFS (local fish store) I have never had luck @ HD,Rona.