What are some examples of satire from Pride and Prejudice, and how does Austen use satire to influence the reader's attitude to the characters?

As you know, Pride and Prejudice is a social satire; so it is difficult to narrow down one's answer to just a couple of examples, but I will try!

First, Austen uses the novel to satirize her society's view of a woman's role during the time period (late 1700s).  Mrs. Bennet, Elizabeth's mother, is the epitome of the stereotypical lower aristocratic woman of the era.  She is most concerned about making the best match for her daughters, feels that she has nothing else to worry about but seeing her daughters married, and relies upon her husband for all needs. Jane, while much more likable than her mother, falls into this category as well.  She wants to marry for love, but she also sees her society for what it is and realizes that she might have to marry for position.

Austen also satirizes the arrogance of the extremely wealthy aristocrats toward the country folk.  Darcy, Ms. Bingley, and Lady Catherine all play a role in this part of the author's satire.  Mr. Darcy and Ms. Bingley disdainfully critique the country dances and culture while making smarmy comments that they think the "country folk" are too ignorant to understand.  Lady Catherine believes that her position and wealth entitle her to control others' lives, including ordering Elizabeth not to marry Mr. Darcy.

In answer to your second question, Elizabeth is most often the "voice" of Austen's satire.  Through Lizzie's eyes and mocking attitude and words, the reader sees the characters as Austen wants them to be perceived.  Elizabeth treats Mr. Collins as a silly, awkward, cowering little man, and thus, the reader views him that way too (Austen uses this to satirize the control that the wealthy had over poor religious "leaders" of her day). Likewise, Elizabeth condemns Darcy for his condescending attitude toward her friends and family, and the reader tends to think that the country characters are mistreated. So, for your second point, you can use Elizabeth for almost all of the other characters to determine what Austen satirizes about her society and why she does so.