You're asking the right questions. Here's some answers. They'll lead you to more questions but we'll get ya through lol. The reef keepers around this forum have been instrumental in me getting my tank figured out.
2. A reef consists of a SW tank that is home to more than just fish and snails. It means you have coral and other invertebrate inhabitants with or without fish. There are (basically) two types of SW tank. One is the reef. The other is Fish Only. You can keep fish only with (FOWLR) or without live rock, though I highly recommend live rock. It'll help you maintain your water quality and provide good hiding places.
1. You have to answer the above question before you can properly answer this question. Lighting depends on the tank you intend to keep. A fish only tank has very little lighting special needs. As long as it's flourescent and nothing in your tank needs light to live you can use a standard strip light. FOWLR tanks should be lit with some type of flourescent at 3 watts or more per gallon of tank. A reef tank lighting can get a little more complicated. Lighting a reef depends on the type of corals and such you intend to keep. If you plan to have easier to manage soft coral, mushrooms, zoanthids and such, then you''l need flourescent lights at about 5 watts per gallon. If you plan for more light needy inhabitants then you'll need to look into Metal Halide. Some corals, clams, and anemones need intense light to survive. Not sure on the recommended wattage for those. I only have a soft coral tank.
3. Mixing salt is a chore to be sure. I fill buckets with either jugs of drinking water from Walmart or I use my VERY slow purifier. I then add the salt, a powerhead pump, and a heater to each bucket. I allow them to mix basically over night. Then I slowly add the new water in after my water change.
4. I purchased almost all of my setup minus tank and stand at
www.marinedepot.com
Here's my equipment list.
55 glass tank
Current USA Orbit light fixture 4x65W dual compact (about $250)
Aqua C protein skimmer (around $230)
Two 150 W Stealth Heaters (

)
1 Rena Filstar XP2 canister filter (about $120)
1 Filstar XP3 canister (about $140)
The XP2 is going away when I get my sump/fuge going. The XP3 is a biological filter. I call it my external undergravel filter. Basicaly a box of rocks.
Well that should give you something lol. Feel free to ask as many questions as you can come up with. The teacher learns when the student questions.