The best thing to do is make a list of everything you want and then google search each thing then read read read. If you have a question about a topic I think you will find a lot of help on the forums but in my oppinion the questions you have ask can not be answered in a couple of paragraphs.
Other and I would be glad to help you out. very simply the bigger the tank the more it cost and the more it will cost to maintain.
Select the size tank.
Then select what you want to keep in it.
Then we can select lighting
Then we can select filtration
Then we can select flow needs