Starting a 20gal

[Canuckgod420]

Well I dont think you need to be confused.....up until this post all the advice given to you sounds pretty decent....you dont need a 4" sandbed, you dont need 2 powerheads(your not havind SPS), instant ocean is fine salt(used for years by thousands of reefers), and the skimmer should be fine(never used this particular unit though).
Listen...if you take things slowly and add you critters slowly you should have no problems(except the common problems all us reefers encounter, algae outbreaks, cyano, the crazy obsession to expand....lol).
I set up a 34 gallon cube tank for my wife about a year ago with 1 250watt MH and a strong return pump from the sump, a 3" sandbed and she has no other powerheads or even a skimmer. Mostly softies, 1 hammer lps, 5 fish, an anemone and a ton of zoos and mushrooms, no problems at all....in fact I have to trim the softies so often that I want to tear out the colonys and just replace with a frag....lol
I am also in the middle of setting up a 20 gallon for my daughter, just finished the stand and I'm on my way to get her some more live rock and sand(she already has a 10 gallon set up with some rock and sand) I got her a 4x24 watt T5 light so this should be able to grow anything she wants(also no skimmer on this tank). The only reason I have a skimmer on my main display is my bioload is rather large and I have an SPS dominated tank.
Hope some of this helps.