Let's deal with the points one by one
1. Gravity Can we live without gravity ? Answer is undoubtly no, regardless all the common problems we can have with 0 gravity such as going to the toilets or washing. Our body is designed to live under a gravity which value is around 10m/s². We need this gravity for our muscles and organs to work properly. If we remain for a too long period within a zero gravity environment, our body will weaken.
2. Resources supply Living in space is not like living in a city on Earth. You cannot go everyday to the supermarket to buy what you need. You will have to deal with the resources you have locally.
3. Waste As mentioned in the previous point, resources will be limited so recycling is the key. You cannot extract what you need and then burn the waste like on Earth. We have to use materials which can easily be recycled. So organic matter is the key, but not long and complex molecules like plastic.
4. Growing food Unlike this is often showed in most science-fiction moves, you don't need 3D printed or some artificial food to live. We must firstly answer to this important question : Why do we need to feed ?
Every living being (flora and fauna) need matter to grow, develop and replace dead cells. Plants can extract minerals and water from soil and carbon from air with the Sun's help. But we animals have to eat to extract what we need every day. One thing you must know is that we humans have a body disigned to eat vegetals, not animals.
We need a certain amount of vitamins, minerals and energy every day we can find in fruits and vegetables. No need to eat meat (dead food), except if you have some problems to extract them from vegetables (this happens unfortunately).
You will also have to forget the single-crop farming. By using natural techniques (most used thousands years ago) we have an efficiency (in pounds of vegetables / square meter) several times more than "modern" farming, and with no fertilizer, no pesticides and less water. Morover, these fruits and vegetables contain 3 to 10 times more vitamins than their equivalent you buy at the supermarket !
To sum up, since these vegetables contains no trash, you will contract less diseases. Plus, due to their high rate in vitamins, you need to eat less every day (which I experienced). Finally, you can feed them with used water and your excrements.