Blackshark, Im going to repeat some of the things you said.
BTW - Beautiful frontosa...cant wait till mine gets a little bigger.
Some things that worry me. You are buying stuff before researching.
Live sand is pretty much a rip. It will cycle your tank, but not because it has the bacteria, but because all that dead stuff (which might have been bacteria before it was left in a bag at room temp for a couple months) will feed the bacteria.
For a reef I would recommend caribsea's special reef grade aragonite. Its the best stuff out there, if you want to know why...ask.
There is nothing wrong with a hydrometer...I have kept my reef for 8 years with one, have a ton of "difficult corals" and have had no problems. Check, double check. Rinse your hydrometer with freshwater before AND after every reading. Make sure that the arm is not stuck someplace, and that it is free of bubbles. Make sure that the water level is okay, and if you do that, you should be fine.
Skimmer. Whoever told you that you dont need one, has a nasty film on the surface of their tank. Either that or they waste a lot of time and salt "skimming" it by hand. I dont have any filtration on my aquarium aside from my skimmer, my 90# of rock, and a 30% bi-weekly water change. All my wastes read out at 0 during testing. If you want more info on this, ask.
The smallest tangs need at least a 75g aquarium. And even then, I feel bad sometimes. A 125 is ideal, some species need more swimming room.
If I were you I would do this:
Research what corals I want...buy some lights accordingly. Get good filtration, a skimmer, a heater...set it all up on my tank.
When I had all that stuff ready to go I would add the sand and the water, and the live rock I wanted.
Watch your water quality over a couple weeks, doing water changes, removing dead stuff from your rock. (This is easily done by blowing them off with a powerhead. During this time you could also have added your cleaning crew: snails, hermits ect) When your tank is cycled, and the rock isnt having dieoff anymore, you can add your first fish.
After you have all the fish and inverts you want in your tank. (This should have been gradual) You can start getting your first corals. Good luck, and post back with any questions you might have. Your original statement is pretty broad to respond to in just one post.