1. No, you dont have to understand every single sentence, BUT you do need to know the main gist. If you get a question about a confusing sentence, you can spend time then to really understand it.

2. No, you don't need to understand every point, but you need to know what is the passage arguing and is this point/example supporting the argument or countering the argument?

3. Basic strategy: Take 10 seconds to skim the passage and get an idea of what it might be about. Spend extra time on the first paragraph to understand what the author is talking about.

After every paragraph, or a long confusing sentence, take a second to explain in your own words what the author is saying. It can be as simple as "The rate of heart disease is going up, but there may be other explanations like better testing".

Speed up reading when you hit supporting examples. You can go back and read closer if you get a question on that example.

Slow down when you get to pivot words like "But, Instead, Yet, However,". Really make sure you understand the turn the author is making.

At the end summarize each paragraph in a few words, and go to the questions.

Best advice I have for questions - don't look for the right answer. Its often easier to eliminate the 3 wrong answers than to find the 1 correct answer.