The only way you would receive these tweets is if they are retweets or if you are following them.
If your account is private then only people that are following you can see your tweets. It doesn't matter who you are following, they must be following you to view your tweets. So, if you are following someone but they aren't following you then they won't be able to view your tweets.
It expands the tweets to show you if anyone replies to them, and who favorites and retweets them.
You can block them by clicking on the "block [username]" link found on users profile pages. Twitter well then show you 2 buttons asking you to confirm that you really mean to block this person from following you.
You can't see who retweeted you on certain applications, such as Tweetdeck for iPhone and such. However, on web, you go to your homepage, and below the bar where you enter your tweets is a bar that has Home, Mentions, Retweets, Searches and Lists. Click on the Retweets button, a menu will drop and click Your Tweets, Retweeted. Click on the tweet to see who retweeted said tweet. Sometimes you cannot see who retweeted it because the person has a private profile and you're not following him/her.
If you protect your updates, the people who follow you CAN see your tweets, but ONLY the people who follow you.
Yes they will get your tweets. It will appear in their @replies tab.
The only way that your tweets will appear on their timeline is if they are following you. If you want someone to see a tweet but they aren't following you then you should 'mention' them in your tweet (@username)
If you go to your to the sidebar where it says home, you go down to where it says "Retweets," click on it and then 3 tabs will appear, if you go to the last one, that's where you can find who has retweeted your tweets!
It's not essential but yes you can.
The only thing that changes when you change your Twitter name is the name at the top of the tweet. The content of your tweets and the number of retweets/favorites stays the same.
Yes, anyone who is following you when your tweets are private can view them.
If your tweets are protected then only people following you can see your tweets. If she isn't following you then maybe she has access to an account that is following you.