My stand was a pain to put together also. Had to dig around, but did find a manual in the packaging. I didn't put the back on the stand because I wanted easier access to the back. Someone told me that that might be a really bad idea. So far, my tank hasn't fallen over, but I am definitely NOT recommending you do what I did.
I don't know about the bagged sand. A lot of people say its just regular sand with nothing beneficial. Nothing bad about it, just a waste of money. I would throw in a small piece of shrimp or fish once you get your sand and rock in. If your sand has good bugs in it, your cycle will be shorter. If not, then it'll be longer. I added a piece of fish from my freezer, waited until my Ammonia, Nitrites, Nitrates were zero, then added a couple live fish and removed the freezer fish at the same time. I put the frozen fish into a mesh bag so it would be easier to see and remove.
Have you thought about seeding your tank with a bit of sand from a fellow reefer's established tank?
No problems mixing salt in the tank as far as I know.
I have a Vortech mp20 in my Solana, and I know people who have a Vortech mp40w, so your Koralias won't hurt anything. Depends on what you want to keep.