Please answer this oranda golfish tank question?

  Ok so I have a 20 gallon tank I want to make this my new fish tank, how much gravel should I put in the tank, how long should I let the water set before I start putting fish in? What is the maximum amount of oranda goldfish I should put in this 20 gallon? how many props should I get for this tank, add in some other details that will help my fish live the best lives they possibly can ... thanx so much
Wish I could answer bro to bad all the other jerks on yahoo answers won't