1. Maybe an ammonia source, but the dye off from your rock might be enough. Do you have a test kit for at least pH, ammonia, nitrite, and nitrate? a hydrometer or a refractometer to check SG
2. Lighting is not needed, some people recommend leaving them off so algae doesn't have a chance to grow. Adding the sand and everything will probably cloud up your water a bit so running the filter will help.
3. Filtered water is always best especially for reef. tap water has a lot of minerals that will help algae grow. I bought salt water from my LFS
for $4 per 5 gallons and DI
water for $2.50 per 5 gallon.
4. I don't think temperature matters but it'll be easier to keep your temp at the ideal level instead of running the heater like crazy to warm it up later