Hi Rees21, welcome to TRT!!! You've found a great place to get some great advice from great people.
Your 3 questions require a very long answer, but I only have time for a short one, so here it is:
1. getting the tank up and running: You'll need live rock and some saltwater. I assume that your nano comes with lights and some methid to move the water.
2. How long before adding livestock: You need to wait until the
nitrogen cycle finishes its first cycle. In short, you can start adding stuff when you can no longer detect ammonia and nitrites in the water. You will need test kits to determine that.
3. Getting water to proper specs: you need to start with saltwater that has the correct salinity/specific gravity. You'll need a refractometer or hydrometer to measure the SG. Then you need a heater to get the water to the correct temp. Most of the other parameters will be fine. If you do water changes regularly (10% every 2 weeks), you shouldnb't have to do anything else. If you have lots of animals in there, you may need, in the future, to add calcium and carbonate to get good growth.
I'm sure others will chime in with more details.
HTH!
