If you protect your updates, the people who follow you CAN see your tweets, but ONLY the people who follow you.
No they will not be able to see any of your tweets. That s the point of having your tweets protected, it protects your privacy from people who don't follow you!
If your tweets are protected then the "retweet" button is not available on your tweets. However, this doesn't stop someone who is following you from copy and pasting your tweet to a new tweet and adding "RT" before it.
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)
As long as you include their username in your tweet (@username) then your tweet will appear in their @replies tab.
If your profile/tweets are not protected then anyone can see your tweets.When you mention someone in your tweet, that tweet will always appear in their @replies tab whether they are following you or not.
If you included their full username (@username) then that tweet will appear in their @replies even if your account is protected.
If your account isn't protected then anyone can go to your profile and see your tweets. Similarly, your tweets can appear in search results. For example, if someone searches "dog" and you mention "dog" in one of your tweets then it will appear in the results.
You can't send a private message to someone who isn't following you, but you can send a reply using a at (@) followed by the person's username and your message. You can do this by Mentioning them or by replying to one of their tweets.
People won't be able to use the Retweet function on your tweets if your tweets are protected. This doesn't stop them copying and pasting your tweet and retweeting the old way though.
The plural form of tweet is tweets.
You can block them - you won't see any of your tweets when you do.
If someone has blocked you on Twitter, you'll be able to send tweets to them, but it won't appear in their mentions. The only way they'd be able to see it if is they unblocked you to see it. They will be able to tweet you as normal, but they won't see what you tweet them.
Any Twitter user can send you a tweet if your account/tweets aren't protected.