Ready to fill tank with water

[Chammy]

Looking for advice, or a step by step to getting my reef tank going. I apologize ahead of time if this is posted but I couldn't find any info.

Anyway, tank is ready to go. So I'm wondering what ratio of salt to water goes in the tank? Running a 90 Gallon

And in doing this, am I safe to get my sand in the bottom while my water cylce stabilizes for the next step...adding rock...and/or possibly somefish?

And while I am waiting for the tank to settle down, where would ideal temperature range be for reef fish?

Thanks again. This community has been quite helpful so far.