I'd like to give you a big welcome to the hobby. Just remember this, patience means time, but with time will come success in your tank. You will have problems and there will be times where your tank is just outright amazing, but you
MUST put in the effort.
Both 10g_Nano and Dave are great success stories of what you can accomplish in this hobby, in small tanks in small time.
I remember when both of them joined, both as clueless as the next, but the one thing that led them to success is that they were willing to learn.
Now, for your questions.
You
will need a powerhead. I would recommend 2- Koralia 240's for Softies and LPS and just really good outright flow. Or 1- 240 and 1- 420 For SPS too.
As stated, stock light will not support any corals unfortunately. A par38 bulb is usually your best bet when it come to 10g tanks. One from: Reef Koi, Coral Compulsion, or Rapid LED will all do good.
In a 10g you are generally limited to 2 fish in the tank. Though it varies, as say the Bioload of 2 Neon Gobies, is none compared to that of a shrimp goby and a possum wrasse. There are also plenty of shrimp you can keep in the tank, so I wouldn't worry about that. Check out liveaquaria.com for fish stocking suggestions.
Live rock, Dry Rock, Macro Rock, whatever is fine. You'll want just around 10lbs. However I keep 20 in my 10g, just for more biological filtration.
Here is a link to a
Sand Bed Calculator so you can figure out how much sand you will need for the depth you are looking for. Again, live or dry sand does not make a difference.
Corals really aren't as hard as they seem. So starting off with them, would be good. As long as you keep up with your water changes, you should be okay.
Your filter is perfectly fine, don't worry about that.
Generally skimmers aren't needed on small tanks like this.
Again welcome to the salt side of things, and ask away.
I have already setup a bigger tank and waiting to transfer my live stock over......MAJOR ADDICTIVE saltwater is hahaha.
