Muggles' Guide to Harry Potter/Characters/Alecto Carrow

Overview
Alecto Carrow, sister of Amycus Carrow, is a Death Eater. When she is initially described, all Harry seems to notice about her is her repeated, almost-nervous giggle.

Goblet of Fire
Alecto and Amycus are two of the Death Eaters who were summoned after Lord Voldemort's rebirth. While their names are not mentioned by Voldemort, their membership in that group is strongly implied by Snape's comments in the early chapters of Harry Potter and the Half-Blood Prince.

Half-Blood Prince
Severus Snape mentions the Carrows when he is talking to Narcissa Malfoy and Bellatrix Lestrange.

The Carrows take part in the Battle of Lightning-Struck Tower. Both of them are at the top of the tower when Snape kills Albus Dumbledore. As Harry chases Snape through the battle and out the front door, he sees Alecto dueling with Minerva McGonagall before fleeing with Snape. We later see her on the grounds where she escapes along with her brother and Thorfinn Rowle.

Deathly Hallows
With Snape being appointed Headmaster of Hogwarts, and Charity Burbage having been killed by Voldemort, there are vacancies for Defence Against the Dark Arts and Muggle Studies teachers. Alecto Carrow is given the post of Muggle Studies teacher. Neville Longbottom tells Harry that, under Alecto, Muggle Studies seems to have become institutionalized hatred of Muggles, promulgating falsehoods about how Muggles are a lower order, dirty and stupid.

Alecto, told by Lord Voldemort to expect Harry to visit Ravenclaw Tower, has herself let into the Ravenclaw common room before Harry's arrival. When Harry steps out from under the Invisibility Cloak to examine the statue of Rowena Ravenclaw, Alecto sees him and summons Voldemort by touching her Dark Mark. She is then Stunned by Luna Lovegood, who was accompanying Harry, and had remained under the Invisibility Cloak. Bound by Professor McGonagall, she takes no further part in the story.

Strengths
Alecto compensates for her lack of intelligence by the use of unrestrained violence and Unforgivable Curses, most notably the Cruciatus curse. It is debatable whether this could be considered a strength. At the very least she seems more intelligent than Amycus.

Weaknesses
Alecto is not particularly intelligent. When her brother Amycus is unable to enter Ravenclaw tower, eventually he forces Professor McGonagall to open the door for him. Professor McGonagall at that time says that Professor Flitwick had earlier opened the door for Alecto, leading us to understand that she also was unable to answer the eagle's-head door knocker's query.

Relationships with Other Characters
While there is apparently some closeness between herself and her brother, Amycus Carrow, the only dealings we see her having with other people are situations in which she is operating from a position of power, or dueling. Her usual mode of interpersonal relationship seems to be taunting. Unlike other Death Eaters, Alecto trusted Snape immediately upon his return to the Death Eaters.

From her treatment of the students, as related by Neville, we can safely guess that Alecto disliked any sign of independent thought from the students. In this, she seems to be following Voldemort's lead with his own underlings.

Questions

 * 1) Why did Lord Voldemort select Alecto Carrow as a teacher at Hogwarts?
 * 2) Was Alecto Carrow a good choice? Explain.