Why is it that the 3rd person pronouns "is, ea, id" sometimes mean "he, she, it" and other times mean "that" or "those"? How can I tell the difference?

This was one of the nuances of Latin that confused me the most when I started learning. The answer is actually pretty simple. If the pronoun stands alone in the sentence (i.e. not agreeing with anything), then it can be translated as he/she/it. If it is next to another noun in the same case, then it is modifying that noun and should be translated as "that" or "this".

What is the stream of consciousness technique, and how can I make it easier to read?

The stream of consciousness technique is employed by an author to articulate a character's train of thought. It is essentially the inner monologue of the character's mind. Think of the way we think. We don't always form full sentences in our minds and our thoughts tend to wander. Only we know how our thought pattern works, so it's difficult to read someone else's train of thought. I would suggest identifying the beginning and ending of a particular thought and putting brackets or a periods around these clauses.

How can I avoid getting caught up on difficult, time-consuming questions so I can finish the English section on time?

The English section can be quite a time-consuming section, that is if you don't know what you're looking for. One of the best pieces of advice I received was that the simplest answer is usually the right one. You don't want to overcrowd your sentences with lots of information that doesn't help the meaning of the sentence. My strategy was to locate the shortest answer and see how that fit into the sentence and if it helped strengthen the meaning of the sentence.