Interesting questions for a newbie. Lets see if I can help bring you into the light.Think of the plant as a person/miner and your closet as a mine. How long would the miner live without fresh air or food if trapped by an accident? Without fresh air nothing will live without food/nutrients nothing will live.

In order to live a plant needs a balance of food/water/air just as humans. If you plan on growing your knowledge base must be deep and extensive. Don't expect everything to be handed to you. You must be willing to seek it out and learn from others experiences. That will require reading not just here but other sites/sources as well.

The one plant idea needs to be looked at as well. Unless you like wasting your time you should expand that to at least three. After you do a little research you will know why.

Loco