When I brute force, I do what you do. It helps me as often as it "hurts" me in the sense that yes, sometimes the right answer was A and I could have saved time. Other times, the answer was E and I found it almost right away by looking at easier to test ACs. I don't think you need to dedicate much brain power to things like this because it is really just a game of chance where the right answer was placed. You're better off establishing a protocol and following it. I wouldn't waste a single thought on "oh if my system here was different I would have got there sooner." If your system is refined and you use it well, you will have enough time to finish every LG section with high accuracy.

Skip and discard the notion that early questions are supposed to be easy. They often have the "easier" questions in the early portion, but that is not universally true. Many 3, 4, or even 5 star questions have appeared early in almost every single LSAT. Many 1 or 2 star questions have appeared late in the sections. There will be hard questions in the early batch. Don't worry about them. Difficulty is subjective anyway, what's hard for you might not be hard for me and vice versa. If you get stuck, flag and skip no matter how early in the section you are. I had a PT yesterday where I got all of the "hard" questions right in a section and a 1 star question wrong. It was like the second or third question overall, and I just moved on. That 1 star question broke my brain and I couldn't figure it during the test. It did not stop me from getting to the end of the section and doing well on the rest of the PT.

To your first question, yes but it goes deeper than that. The real flaw is that it is not a necessary assumption. When you look at questions like this, look for common traps. As JY said, a common trap is including a strengthening answer choice in NA questions. Does B strengthen the argument? Yes! to the point that it is nearly air tight. Answer B provides a ton of strength, if it was true the editorialist has some strong evidence of their claims, but it is not needed for the argument to function.

The best way to test if a clause is necessary for an argument is to negate the clause and then see if it destroys the argument overall. The argument loosely says that people OFTEN portray themselves as they wish to be perceived. What happens when we negate B? What if B said "it is not the case that ALMOST EVERYONE who answered a certain way continued watching?" Well the argument that people often portray themselves a certain way still functions. You don't need "almost everyone" for the argument that "people often portray themselves how they wish to be perceived" to work. You could have half of the people, a quarter, 10%, any number of people doing the thing described would be enough to satisfy the argument. No matter how strong the argument becomes with B, it never needed B to be functional.

A lot of people will put forward what worked for them as the gold standard of behavior. This is not unique to the LSAT, people do this for everything. I can share what works for me, but it's disingenuous to say it's the best or only way to do something. This isn't a cram test, it is a skill check. You probably will not make any breakthrough or improvement the day before the test, but you certainly could. You could also stress yourself out more and hurt your performance on the real thing. You need to know yourself and then do what's best for you. I will be doing the "5 hardest games/passages/lr questions" the day before my test, but I know that I won't get psyched out by doing poorly on those. I see it as a last minute check for my ability to read through answer traps, and will keep that info in mind on the real thing. Some people might be better served by taking a break for a few days before their test. This late into studying, seeing what traps you routinely fall for could mess up your mental game on test day. Taking a break lets you separate yourself from that a bit, and a lot of people said they got their best scores after a short break. You're the only one who knows what's right for you. As for studying the day of, absolutely not for me. I will do a super easy game and some easy LR questions to warm up, but that's it. I am not taxing myself mentally at all before I sit down on Saturday.

You currently have four total sections on the real test, with one being experimental.

Also locked out. Very annoying, hopefully it gets resolved shortly.

Another way to rewrite that answer choice could be "IF something is a celestial object AND it does not have Lithium, THEN it is not a brown dwarf." So yes, that is absolutely correct. A star with no lithium is, as answer choice C indicates, not a brown dwarf.