The previous post gave some excellent answers to your questions. For the most part, the children try to avoid Aunt Alexandra's suggestions since they often conflict with Atticus' own good advice. However, she does show a few positive traits at the end of the story. Following Bob Ewell's attack on the children, Alexandra laments that " 'this is my fault.' " Alexandra had a premonition earlier in the evening that something bad was going to happen, but no one took it seriously, and she and Atticus remained at home, allowing Jem to walk Scout to the Halloween pageant. After helping Scout out of her costume, the motherly side of Alexandra finally emerges. She calls Scout " 'darling,' " and then, in her finest moment in the novel,
... Aunty brought me my overalls. "Put these on, darling," she said, handing me the garments she most despised.
Scout was not oblivious to Alexandra's act of kindness (though the unconscious Jem was), and one can only wonder how Atticus' sister treated the children thereafter.
If ever there was an example of character foils, Miss Maudie and Aunt Alexandra are it! Miss Maudie is a clever, witty woman who befriends Scout and Jem. She tries to mother the motherless children whenever she can. She jokes with them, bakes them goodies, and tries to give them good advice. It is she who tells them that their father "can do lots of things" and that they should be proud of him. It is she that tells them the horrors that poor Boo Radley has had to suffer at the hands of his dysfunctional family. She comforts Scout many times in the novel, and she has a wicked sense of humor. She teaches them to be humble.
In contrast, Aunt Alexandra is a type of social snob. She is haughty and proud of her so-called "fine" ancestry. She constantly encourages Jem and Scout to remember their ancestry, remember who they are. She tries to make the children into something they are not. She tries to force Scout to wear dresses and insists on calling her Jean Louise. She is a hypocrite who enjoys being with the two-faced ladies of the missionary group. Alexandra has a good heart, I think, otherwise she would not have agreed to come and help her brother out. Plus, there are instances where she has her come-uppance, especially with things Scout says that are wise and "out of the mouth of babes," but Aunt Alexandra is very concerned with appearances and family and properness. Most of the time, these attempts to civilize Scout and Jem drive the children crazy. Alexandra thinks that Atticus has been too lenient with the children, but Miss Maudie does not agree with this. She believes Atticus has done a great job of raising the two children on his own.