I've often asked myself this same question. How do other people practice and learn new techniques.
We share a similar beginning, I started getting into synths and effects a couple of years ago, without knowledge of how to play an instrument or write a song. But I read a lot, bought some equipment and began to understand the basics of subtractive synthesis.
Last August I started building a eurorack system. I bought too many modules, way too fast. It's been exciting to get hands on so many great sounding modules, but I've found that my time in front of my system hasn't been very focused, at all. I've been nagging myself to come up with a more deliberate way of spending my time, something more structured, that's building toward achievement of an ultimate goal. I often think it would be easier to stay focused if I had a friend who was also into synths, we could work towards something together. Then I think to myself that I could likely find a bud to learn with online someplace, but I feel like I'm at my best when I interact with other people in person. So I end up spending my practice time doing basically everything you listed, but sporadically and without much focus.
I think all three approaches mentioned in your post are valid and will lead to an accumulation of knowledge, ability and confidence. For myself, I think it's simply a matter of setting specific goals, planning out my practice time, taking notes & recording sessions, and perhaps making more of an effort to meet people online who are also learning and looking for friends. :-)