The best first clue for this sentence is the clause "expressing his passing thoughts with little hesitation." This means that Robert apparently did talk about his views. To "opine" on something is to express one's opinion on the matter, even if one is not certain of the truth of the matter. (This is the nature of opinion.) It seems that he would express thoughts in just this way. Thus, it seems that he does not have any really "set" beliefs. Hence, "settled" is good—though "certain" and, perhaps, even "dogmatic" both could work if the other words were well-combined with them (though they are not). Since Robert's friends are described as being reticent and conservative, they likely do not express matters of opinion this freely. (Note, this has nothing to do with conservatism in the political sense but instead with the general temperamental outlook of being cautious about new things.) Such people would be disconcerted by his opining, and this would lead to feelings of anxiety or consternation.

A number of these possible answers do have a correct word (or set of words) for the second blank. This needs to be something like "colder" or "brisker." However, the key blank is the first. It clearly needs to be opposed to the word "literally." The point is that most people use words in ways that are not literal, even when they say they are speaking "literally." A metaphorical use of a word is one that is extended, as when we say that the glass is "sweating" when what is really occurring is condensation. The last blank, likewise, is quite obviously something like "initially" or "originally." 

The simplest blank among the three to be completed is the final one. The last issue with the argument is that it had something that "did not logically connect the ideas being expressed." In logical reasoning, inference is the procedure of drawing conclusions by means of the successive progress of reasoning. Another kind of error is "equivocating," which happens when you change the meaning of a word in the middle of an argument. For example, this is an equivocation: "All banks [of rivers] are muddy places. I went to the bank [i.e. the bank building] to get money today. Therefore, I went to a muddy place." (Of course, the brackets would not be there if the equivocation were to happen. They are merely there to help you understand.) Finally, a "sound" argument is one that is logically well-founded.

This sentence initiates a contrast between Patrick and Isaac by using "although." It seems that Isaac becomes drunk very easily; however, Patrick does not become inebriated in this way. (The word just means to become drunk.) It seems that Isaac fears being in a drunken stupor—that is, a state of unconsciousness (or at least semi-consciousness). Thus, he remains sober—in the sense of avoiding alcohol. (The word can also mean serious—a person who is not drinking might well be a serious temperament.)

This sentence has a contrast in it, as indicated by the use of "no . . . but instead." The first direct clue for the word meanings is "given their import." The word "import" can be used as shorthand for "importance." Therefore, the matters are "quite important." To be "consequential" is just that—to be of import and creating consequences in the world. The contrast to this is "ephemeral," which means passing or existing a short while. This can have the extended sense of being passing and unimportant. Since these are important, it makes sense that these topics were controversial. Important matters almost always spark arguments!

The word "dire" means extreme. We use this sometimes in the expression "dire poverty." The word "straits" means a state of difficulty. Now, it is likely tempting to choose "fortunes" or "need" as well; however, the coupled pair for the first two blanks must be contrasted and relative to this idea of being in dire need.  We know the contrast must hold because of the "although" construction.  Particularly, the contrast is between what Odo appears to be and what he can be at times (by helping the needy). To be "altruistic" is to be "other-focused." The "altr-" portion comes from the same basis as "alter" and "alterity," both of which refer to "otherness." This action seems to be in contrast to his normal way of acting, so it is astonishing to his friends!

This sentence implies that the moral system was beautiful because of its balance. It seems to be contradictory but in fact is well "balanced." The word "regulated" only works partially in this manner and is paired with words that are not as appropriate for the sentence. In any case, "regulated" does not express "balance" well enough. The idea of "overall structure" is expressed by "architechtonic," which can be taken to mean the "overall architecture" of something. These well balanced parts can be said to be "in harmony" insofar as they are balanced and function very well together. This is how harmonious music "works" as well—by such careful balancing of pitches and tones.

The first blank is relatively easy, for the best noun for a group of disconnected things is "jumble," which describes a disorganized pile of things—though the expression can be metaphorically transferred to "things" like thoughts as well. The word "instead" indicates that it actually was something quite different from such a jumble. It was organized. Therefore, its topics could be said to be "interwoven." If they are so, it also makes sense to say that they are an "arrangement," which is well contrasted to the "jumble" spoken of in the first part of the sentence.

This sentence's logic indicates that there is a contrast between being excitable and the word needed for the first blank in the sentence. In contrast to being excitable, "imperturbable" means unable to be excited. When we are "perturbed," we are vexed or excited. The "im-" prefix is privative, meaning not. The second blank is a synonym for this first blank. To be "stolid" is to be calm. Finally, the indication in the sentence is that it is unthinkable that a stolid person would be capable of having such wild emotional swings. This is why it is amazing that one person can have both of these personality aspects. Hence, one would think that such a person would be incapable of such swings.

Clearly, Paul's family thinks that he is making horrible choices. This is the best defense of the option "abominable." It might be tempting to choose "questionable . . . outcast . . . laudable," for the second blank needs to indicate the fact that Paul is being cast out from his family contacts; however, "laudable" means praiseworthy, so this is not a good answer. A "pariah" is an outcast, so this word works well for our purposes in this sentence as well. The introductory clause does not necessarily have to state that Paul's actions were good. It may well be that they are private—in contrast not to their "abominable" nature but, instead, to the public act of his family's shunning of him.