I have found that reading somewhat complicated literature, like college textbooks (bonus points if they’re law related :smile: ) outside of my regular LSAT study has been beneficial for me when it comes to the issues you describe with missing words or skimming RC passages rather than interpreting them. While reading books that are especially challenging, I try to hold myself accountable at the end of each page by asking myself, “What exactly did what I just read mean?” By doing this, I have seen strong improvement in my ability to read RC text effectively.

As for your second issue, my only suggestion would be to drill those question types more and watch the explanations for questions you struggle with, not just those you get wrong. The language used in many answer choices throughout the Flaw and NA categories is similar, and eventually patterns will emerge with practice.

Best of luck! I hope I could help.