P. 1: The Kaplan method for reading comprehension begins with the passage. Ideally, you should have a good idea of the answer to Global questions before you even get to them.
In this case, the author's first paragraph describes a phenomenon--the low death rate despite the brutal penal code. The second paragraph and the third paragraph both provide partial explanations for that phenomenon. The author's purpose, therefore, can be summarized roughly as "explain why the death rate went down despite so many crimes being capital offenses."
C matches that prediction perfectly. Remember that on Global questions, you can begin with a vertical scan; A, D, and E can be eliminated by their first words, "Outline," "Evaluate," and "Define," respectively.
That leaves us with B and C. B is tempting, but too narrow; the King only shows up in the second half of the passage, and the author's earlier discussion of the "simple decency" of the population is unrelated to the Royal Mercy. B, therefore, cannot be the purpose of the whole passage. It can be eliminated. C is correct.
p. 2: Petty theft and "Posing as a Gypsy" are immediately preceded by the word "but." This indicates contrast; we should take a peek at the lines before them.
What we find is a "not only...but [also]" construction (looks like we made a typo--Not Only will ALWAYS be followed by But Also on the GMAT). So we are contrasting "murder" with "posing as a gypsy." Why would the author do that? Well, D covers that one pretty well.
A is a distortion; petty crimes were punishABLE by death, but according to the author, the courts seldom followed through. B is out of scope; we have no reason to believe posing as a gypsy was common. C out of scope as well, since the passage makes no mention of modern laws. Finally, E distorts facts the same way A does; the author's point is that the sentence was seldom carried out.
3. This is an NOT question. 4 of these will be true based on the info in the passage; the correct answer will directly contradict what we know. B contradicts line 15-17: judges can commute death sentences, so aren't bound to the letter.
A is stated in lines 18-19: "the law demanded...."
C is stated in 20-22, describing juries' decisions to convict for lesser thefts.
D and E are both stated in lines 29-30