Welcome to the salty side. It's a lot of fun
On the sand, looks like you've got the "Bahama oolite" or similar. It does get blown around like crazy. I still use it because I love how it looks, but you need to play around with the flow to make sure it doesn't end up all in a big pile. Any larger grain sand will not give you this problem- I recommend aragonite.
For the cycle, personally I would just let the live rock do it's thing, shouldn't take very long. You could add a little bit of ammonia if you want but the die-off from the live rock will fuel the cycle itself, so don't need to.
Your hitchikers are dwarf blue leg hermits, and some snails. The worm looking guys are vermetid snails, a bit of a PITA but not the end of the world, I have them as well.
