If the person has email notifications enabled for new followers then they will receive notification that you started following them again. They won't be notified that you unfollowed them though.
No they are not notified.
You can block people from following you on Twitter from their profile page. Click on the gear icon on their profile page and select "Block or Report" from the dropdown menu. Select the reason for the block and click, "Block" to confirm.
The only way to delete someone who is following you is to block them.(Go to their profile and click "block")If you want to delete someone that you are following then go to their profile and click "unfollow".
To not receive tweets from someone on your homepage, unfollow them.
To unfollow an individual or a board:Log into your Pinterest account.Go to your main page by clicking on your user name in the upper right hand corner, and click on "Boards."Click on "X Following" on the bar above your boards.Find the individual's account you want to unfollow, and click on "Unfollow."If you are only following a few of their boards (and not their entire account), you won't have the "Unfollow" option below their name. So you'll need to click "Follow", then "Unfollow."If you only want to unfollow one of their boards, click on the user's name, and you'll land on their main page. You can then click on "Unfollow" on the boards you want to stop following.
Even I looked all over for this, but to no avail. So, I made one myself. Check it out here. It's called TwitWipe. (see related link #1)
yes
It is impossible to send a DM on Twitter to someone who isn't following you. The user has to follow you before you can send them a DM.
At the top right hand corner it tells you how many people you are following and how many people are following you. If you click on those that are following you, they are in order of when they started following you. So, the one at the top is your most recent follower.
I think you can follow someone on Twitter if you have 900 K people already. It should not matter how many people you are following or who is following you.
It means "Someone I'm Following"
Someone that you are following would have "retweeted" the tweet.