about 1 cup of salt per gallon is standard(from my experiance atleast)
Use your refractor(they are great and save you time/inaccurate readings)
TAKE YOUR TIME If you rush, you will either mess things up. Or wish you had done things differently.
You are going to have this tank for a long time, 2 or 3 months wont matter in the long run.
Get rid of all the old water.
I would even sugest buying the "pre-packaged" real salt water that is sold in 4.4 gallon jugs.(you still need an RO/DI to add fresh water, in general)
Its from the ocean, so you know its good.
Good water/live rock/live sand will be a huge help to you as they act as a buffer and will help correct the small mkistakes you make.
You also need supplements(once you have fish/coral).
I would recommend the
ESV(2 part system) most vendors on here carry it. Its a 2 part liquid you add to the tank to correct PH, mag, cal, alk, most of the things you need. And then phytoplankton, for filter feeding corals/inverts(kent makes some good stuff).
You dont need a clean up crew until, YOUr tank has cycled(about 4-6) weeks from when you start, AND you are feeding the tank(if your not feeding the tank, the clean up crew will have no food)
I am also new to this hobby, but this is what Ive learned so far.
GOOD LUCK
and Manhattan Reefs is awesome, these ppl really help!!!