Welcome to Canreef!
I'm not familiar with most of the equipment that you listed, but with the other things:
How large are the overflow holes that you mentioned?
You will probably be needing to be vacuuming your sand as part of maintenance, so appearance is what would be most important. There are different colours - white, pink, black. Caribsea select size would do. I wouldn't go too much bigger. 2" depth at the most.
Get at least one piece of live rock to go with your eco rock and let the sand and all the rock live in your fully set up and running system for around 4 weeks. The best indicator is your ammonia. Test your ammonia level every few days. Once your ammonia registers then goes down to zero,you can start adding other livestock slowly.
Let us know what your livestock wish list is.
Mitch