Personally, I think fiji rock looks the best, but it's a personal choice. Hopefully you won't get a 7 foot worm in a 10 gal tank!!!
A sump is basically a second tank hidden away from your main display tank, that holds your heater, skimmer/filtration, can have a refugium in it, or other types of filtration & equipment. Having a 10 gallon actually would make it even more beneficial than in some larger tanks, simply because of the benefits of adding so much more volume to your system, making it a lot more stable.
That being said, it's not necessary, but you may consider it in the future, especially if you run into any problems with water quality/etc. What I can say, if you DO run into these problems, you might expend more time/money/effort trying to fix these problems than a sump would cost you. It can be a big project for someone new, though. I personally don't have a sump in my 75 gallon, but on my 125 gallon upgrade, I'm going to put one in for all the benefits it adds.
Like others and I have said in other posts, you'll have your hands full to manage that tank's water quality. A refractometer (over a hydrometer), a good test kit, and maybe even a temperature controller are going to be very important for you.
Hope that helps,
Alex