'Ne' is one of ending particles that add various emotions to the statement. The primary function of '....ne.' is to seek an agreement and/or confirmation from listener. 'Ne' invites the listener's cooperation and engagement into the conversation by agreeing the statement. If the intonation is up at the end ('.....ne?'), the sentence becomes literal tag question, which is expected to be agreed. You can use 'ne' both in polite speech and casual speech. (example) "Kono neko, kawaii desu ne!" :polite "Kono neko, kawaii ne!" :casual (Both means "This cat is cute, isn't it!") However, over-use of 'ne' should be avoided. As it creates agreeing atmosphere, too much 'ne' may sound too intimate and too pushy. Then, how much is too much? Probably it will be safe to use it only in situations where you'd use tag question if in English. Also, 'ne' is only used in conversation. Never in formal writing. As other answers indicate, 'ne' sometimes sounds feminine because it makes the statement rather softer than simple declaration. Especially, '...wa ne.' '.....no ne.' are used only by female. But I think 'ne' as an agreement seeking mark is no problem for men to use. (Men who want to show off their masculinity would avoid 'ne'.)

yoroshikune: {ne} doesn't have specific meaning. it's added to the end of the sentence. It's used when you ask someone or want to mention to others what you want to say, your mind or suggestion. I think there many words in English you put at the end of the sentence as in "please""right" also like "boy" "girl" "babe" "dude" etc,. they don't have specific meanings. {ne} would be same use here. {ne} is something we often use in our conversation. on the less I don't recommend using {ne} too much. I have many non native Japanese speakers their Japanese is good enough but sound awkward when they use {ne} too much. {aitakatta} is "I wanted to see you". this person missed to meet someone or missed/miss someone.

The best analogy I can think of is like how in English, we sometimes increase the pitch of our voice to indicate that we want to reaffirm answer. Also, 'ne' does have a feminine connotation. For men, it is not usually used in informal conversation.

It depends on the sentence; Once you add "Ne" in the end of sentence, the sentence turns into a questioning sentence. It is pretty much similar to ",isn't it?" or "aren't you?". In this point of view, "Ne" could be used for an agreement. There is an exception; however, in women's conversation, "Ne" could be used very often; This is purposed for "emphasis of femineity ". In this case, it's not be turnning into a questioning sentence. So if you are a man or guy, I recommend NOT to use it much. >What is the meaning of ''aitakatta?'' aitakatta's meaning has been explained by former anwerer. If you add "Ne" in this sentence, the meanings will turn to be weird... "I wanted to see you, don't I ?" or "You wanted to see me, don't you?" Aitakattane. (I wouldn't use it.)