Hi, welcome to the forum!
I would recommend 2 powerheads for your tank, maybe 2 550 or 750 koralias. Unless you like the wave feature you can also do that, but I just use the powerheads the old fashioned way in my tanks.
I would go with sand over crushed coral, and the "live" bagged sand while it can be used, I'm of the mindset that theres not much "alive" in that sealed bag. lol
I would aim for a total of about 50lb of rock. You can buy 40lbs of base rock, or dead rock and the rest in "live rock" and it will seed the base rock. I would also say to get as much of your rock in at step one, makes it easier and better. If you buy live rock after the cycle you'll have to cure it in a separate container or tank.
Hope that helped some, and again welcome aboard!