You put 5 questions into one. You can't do that. As editors we are required to answer only one when and if you do. So, I edited the rest out and am presenting answer to the first one you posed.
Aunt Alexandra attempts to make Scout a lady by forcing her to wear a dress. Of course this significantly burdens Scout. But there is an important female occasion at the house which merits wearing a dress. As Aunt Alexandra hosts the Missionary Society Tea she wants to have every appearance fit the event which includes her niece's apparel.
Having Scout attend the tea is another way in which she will learn how to be a lady. She was forced to have conversations and practice appropriate use of language under the circumstances.