I can see how you are very enthusiastic about lucid dreaming. The most important comment first: don’t ever forget to have fun. If you are not enjoying doing the techniques, for example, then you probably shouldn’t until you find some motivation again 
I think you can abandon that belief. Maybe it is quite common for the first LD(s) to be on the shorter side, but that would be due to excitement or whatnot. There is no reason to belief that your LDs cannot be on the longer side, too, which is a much better prospect to keep in mind.
I think it was a good decision to take a break. Many people have more LDs during their breaks than during their active periods 
Everything needs to sink in properly, I guess. Anyway, just discussing the topic with other people is a great way to get back into useful habits and build up excitement 
Dream journal, yay 
I would agree that the dream journal is the one most important thing that dreamers should have. I am curious about your experience with using an app. Did you also try a notebook version before? I think a physical notebook might actually have a different effect on dream recall.
This seems very indicative to me that MILD is a very effective technique for you. You should seriously give it a try. It really is about setting intent, just like you did with your dream recall.
Well, WBTB is indeed very famous and gets a lot of credit for its effectiveness. But if you cannot make it, then simply don’t. And don’t beat yourself up over it. I think I like 4 or 5 times more LDs without WBTB than with WBTB, as I am also not doing it very often. If I want to do WBTB, I really need to set aside a lot of time and quietness. I definitely can’t do it like an everyday technique. I plan at least 1 extra hour for my main sleeping phase and make sure that I can go to bed properly the first time, so the timer goes off at the right time, and then plan it so that I can go back to bed in such a way that the remaining time is enough to get the dreams before the final alarm that forces me to start my day. It really is quite a big investment each time.
You have a good point. Relaxing when falling asleep so you can focus on the technique is quite valuable. I am also not really good at it. In general, I can only suggest to practice meditation. The relaxing kind. There are also a whole bunch of other relaxation technique, but most of them don’t seem to fit with me, and maybe you also have the same higher requirement. So I pretty much stick to semi-regular meditation exercises before falling asleep.
I think what you are referring to there is usually called dream incubation. There are various techniques for that, too, and they coincide a lot with lucid dreaming techniques. You can try visualization and auto-suggestion, for example.
I think this is the biggest point you are making with your post. I think you hit it spot on that you don’t even need lucid dreams to enjoy dreaming as a hobby. That is also exactly my attitude. So how can you make your dreams more interesting and more vivid? Try to memorize the following exercise: Stop your current train of thought, put away your phone or whatever you are currently holding, especially if it has a screen. Instead, take a look at your surrounding. Really look at your surrounding. Take in all the small details that you can see. The little cracks in the wall, the small dirt spots sprinkled over the floor, the pattern on the clothes that the people around you are wearing. You may very well be surprised by all the details that you can find, that you were completely oblivious of before. Do the same for hearing, smelling, sensing, feeling, thinking and the idea of your self (not “yourself”). In our modern day of constant distraction, most have unlearned how it is to live in the here and now, in reality. Curiously, this is important for being present in dreams, too. Do this little exercise maybe 2-3 times per day, or a little more, just whenever you think about it. You will not make huge jumps, but it will help you improve the quality of your dreams. Any kind of dream.
I am not a psychologist, but I am sure that is not how the subconscious works. Your SC will influence your desires, but it has no desires on its own. Or rather, it has no agenda, like not wanting you to dream lucidly. I recommend you talk this through with your friend again and try to assert yourself that lucid dreaming is not a battle of your conscious vs. your subconscious, but a reconciliation of them both. The latter metaphor is more accurate I think and definitely more desirable. In a lucid dream, both of these you’s exist at the same time and you want them to be friends, not enemies. 
I like the reasons you laid out. Sounds like lucid dreaming is indeed a suitable hobby for you. Also, people have been shapeshifting in lucid dreams for the longest time, but still I feel your intention is somewhat special and unique, I really like that. Having a proper vision is definitely useful. Let me ask you a question on top of what you described so far. If you become lucid tonight, what are you going to do? Please try to answer somewhat concretely.
Haha I think there are only very few “professional” lucid dreamers. You probably mean experienced or veteran lucid dreamers. Oneironauts is a term I really like (although I feel I may not yet call myself one).
Important final point for today: Don’t wait to share anything until you have a lot of experience. Sharing whatever you already know or what you are currently trying out and which results you get is actually much more important at an early stage in development. I train a lot of new people at work all the time and always encourage them to present something in our knowledge-sharing session, even if the old guys probably already know and maybe know it better. But this way, they can process the information much better themselves, plus there are a lot of other people on their level who can benefit from taking the first steps simultaneously. For example, consider opening a dream journal on LD4all, maybe with some commentary to spice it up 