New to the hobby!

[inspire]

I just started my own 20gallon Reef Aquarium. I am very glad to find a bunch of local enthusiasts here on this board. I started my tank about 1 week ago, I have some questions though, so please help!!
1) What is a refugium? What does it do? How can i set one up? I plan to keep mostly corals like some soft corals, polyps, mushrooms, maybe an anemone, a brain...etc.

2) Is my lighting sufficient? I have 96watts of PC lighting.

3) What is a calcium reactor? How can I make one? Can someone help me out?

4) How much sand do I need for my DSB? Currently, I have about 2" of oolitic aragonite sand. I "think" i need about 4-6"? Am i correct in this assumption?

5) Can someone here PLEASE give me some live sand to seed my own sand? PLEASE!?!?! Thank you!