I am relatively new too and I know it can be frustrating to try and sort out all the wonderful advice you will get here at R2R. They all want to help but everyone goes about setting up a tank differently. For certain things, especially "how to set up a new tank" you will get a BIG range of advice. If you happen to have a good, reliable, well-respected LFS in your area, you are a step ahead. Ask them questions and they can be a great resource. But defining a "good LFS" is hard too. How long have they been in business? How long have the people that work there been there? (ask them!) What is their quarantine procedure? How much are they selling fish for? Where do they get their fish? If they have really cheap prices on their fish and their answers seem geared toward just selling you stuff asap ... beware!
I have a GREAT LFS and my guy there gave me this great advice -
there is often no hard, fast right or wrong answer to many questions. You can do one thing several different ways. A good reef system can happen in various ways, you just have to weigh your wants, needs, budget and time. It is easier to know what not to do, rather than what to do (as there are many variations as to how to set up your first tank)
Here's some things to ask yourself:
How patient are you?
Would you rather get livestock in there as soon as is possible or are you willing to wait for a month or two or even longer?
How important is cost?
What kind of corals appeal to you? (certain corals, the "hard" corals, need more light and lights are very expensive - so you might want to save your money for lights and spend less on the initial rock)
We were faced with the same kinds of questions you have now. We decided to opt for a "middle of the road" route - used a combo of live rock purchased direct from reputable LFS and the rest dry rock purchased cheaply from an online source. We used almost all dry sand and got a cup of live sand from same LFS. We did it this way to save money on the rock and sand. We decided to go slower and save more money at first. But you have a small system, so buying good, fresh live rock from your LFS will not be that much. Starting with all live rock will make your start-up time shorter. BUT you will also get "hitchhikers" in with that rock - some of those critters will be good, some not good. If you start with all dry rock (clean dry rock) and dry sand, you won't have to worry about hitchhikers, but it will likely take longer for your tank to get cycled and reach a stable point.
But very best advice has already been said - take it slow. Understand what you are doing and why. Ask questions right here.
I write really long replies, sorry. Years of being a journalist, I type super fast!

Welcome!