Answer

Hello Shimon.
I’m very impressed by your motivation and your ability to analyze and conceptualize, especially at your young age. Strength to you in Torah.
Despite the motivation and talent, and perhaps because of them, you must not rush too much, and you must not develop exaggerated expectations. You are not supposed to be anyone other than yourself—not Moses our teacher and not Rabbi Shimon Shkop. We’ve already had those. But you also won’t be yourself at age 20, nor at age 25. You need to strive toward the goal with dedication and persistence over time until you get there.
That means there is no need at all to swallow everything now. At this stage, don’t try to create your own Torah; rather, make use of whatever frameworks you can join until you reach the ability to learn independently (I assume you still don’t have that, though perhaps I’m mistaken). For that purpose, it would be worthwhile to try to find a framework that studies analytically and join it. At the same time, setting fixed study partnerships in order to gain breadth in Gemara, and study partnerships on foundational books like Shev Shema’tata and Sha’arei Yosher and others, can certainly be helpful. Everything according to your time and ability. Don’t bite off more than you can chew, because you do not need to finish everything now. Persistence takes you farther in the long run (see the tortoise and the hare of Aesop).
Don’t forget that this year you are finishing high school, and then you’ll be able to find a framework that deals seriously with Torah and join it. There you will certainly be able to acquire tools and knowledge, and then make use of them in life by yourself (or with study partners). In the meantime, learn what you can, and it isn’t all that important exactly what.
1. Unfortunately, here I have to answer just as you expected. Most people learn better with a study partner, especially in the early stages—even if he is your age and in your situation. But if you are built differently and can do it, then of course you can also learn alone.
2. The halakhic rule is: as much as you can, with no fixed and universal quota. And not for nothing. But do it without biting off more than you can chew. Also do what a normal boy your age does: friends, going out, general studies of course. And rest from time to time too. It’s important to stay normal without compromising your spiritual progress.
3. Yes. In the Talmud the recommendation is of course the opposite, but today we are in a different situation. There are books and databases, and the value of sheer breadth of knowledge has greatly declined (though it still exists). It is more important to develop analytical skill. Therefore I recommend devoting most of your learning to analysis, while in the background you can progress in breadth. The best is analytical breadth, but that requires analytical skill. If you reach a point where, from reading the Gemara, you can understand what the main analytical points in the passage are, that will allow you to quickly open commentators and get a sense of what they say about those points. You can also make use of what we used to call “automatics,” analytical compilations arranged by the pages, such as Beit Lechem Yehuda, Nachalat Moshe, and the like.
4. If you are learning for breadth, then no—unless you don’t understand the issue without opening it up. Note: not if it’s unfamiliar, but if it’s not understood. But in analytical study, it is worth opening as much as possible. Again, though, don’t drown. With time you will acquire skill and know when and how much to open.
5. Analytical works on the Talmud and Maimonides are part of studying the passage itself. Alongside that, there is certainly value in setting aside time to go through the meta-Talmudic books. The important question is whether you find a study partner or framework that will help you, and based on that you should determine which book you study.