Well I was hoping that someone else would take this one as they are really big questions and I still think of myself as a beginner. But here goes:

1) How to really observe like an artist? This is what Drawabox is all about when it comes to spatial reasoning. There are many other ways to see like an artist though. A quick google search of "How to see like an artist" will give you pages of results with good answers.

2) How to avoid symbol drawing Once you start reading the answers to the first question, you will find the answer to this one. Once you start observing like an artist, nothing will look like the symbols that you are trying to avoid.

3)Which "free" sites are good... I use this site as a guide: https://www.brendanmeachen.com/soloartist There are others but it will give you a place to start looking.

4) A better way to substitute motivation with to avoid procastination There are tons of videos on Youtube on this topic. But I do think this is a very personal question. I am a great procrastinator but I do it in my own special way. I'm sure you do to. Really think about why you are procrastinating and how you are procrastinating. Start small with small improvements and don't beat yourself up if you fail.

5) A good place to get art supplies I think there are lots of places to get art supplies. However, I would say you want supplies that are good enough to get the job done without getting in your way but don't buy anything really expensive. Beginners in any skill should not be hindered by cheap tools, but they also can't really appreciate high level tools.

6) An art community who will tear your art into small pieces Online can be pretty brutal and putting yourself out there can be scary. Sometimes people are casually cruel and that helps no one. On the other hand, you don't want to be in a space where there is no critique. I think you need to look for someplace, like Drawabox, where people will give constructive criticism. I would be careful of your expectations however. If you are here, then you are a beginner like many of us and quite frankly, we are not very good. The best thing you have ever drawn might still have many flaws. I think it is better for someone to just tell you what's wrong. Hopefully not in a cruel way. Just remember that even the greatest artists you have ever admired, once upon a time, perhaps when they were children, drew really crappy pictures. They practiced and got better.

7)How to identify which parts are important in a reference I think you are asking another question related to your first one. I think a reference is just a starting point. Compositionally, what is important is dependent on what you are trying to accomplish and what you are trying to focus on. Think of a street scene. Are the buildings important? The people? The size of the city? The motion of the cars? What is the lighting? Perspective? Those are all choices that you make with the reference as a guide but not as an instruction manual.

Hope this helps. I would love to hear what others have to say.