You need to read the pinned articles above all of the different sections. There is really too much to sit and list. Start with the beginner section and go from there. They are just above where you post. They will answere most of your questions. Then after you read those you can ask any questions you still have. They don't answere everything, but it is a really good start.
You would really need to read a few of them before you decide which tank. They will help you make a better decision.
I hope this is somewhat helpful.
Welcome to TFF!