Can i get list of character names of my RealID BN Friend Acount?
 

I got friend, he got 8 characters on 3 realms, is it possible somehow to get names of all his characters of my friends account?

I would like to make an addon that can track online status of selected characters of selected RealID BN Friend, without manually input each name and realm.

You don't need to know all the names of your friend's toons, only that he/she is online. You can get the name of any toon your friend is on, as well, if you wish. Here is a search for some ideas.

http://www.wowace.com/search/?search=realid

sort of related, is there any add-on or way to see the last toon a particular battletag was logged into (or any/all toons that are associated with a btag)? even if you haven't accepted them as a friend? i have received battletag invites from people that i am not sure who they are, although i probably know their toons. usually it's a guildie who got my btag from the GM or something, but i like to be sure.

Your addon would need to compile that information itself by keeping a list of every character it saw your friend log into. Based on your description, this doesn't sound like a problem though, since you probably wouldn't care about a character your friend never logged into.

No, and that's a good thing. Random people should not be able to get a list of all your characters just from knowing your BattleTag. There's a reason you have to accept a friend request from someone before they can talk to you on Battle.net and see when you're online no matter what character you're playing.

If you're getting friend requests from people whose names you don't recognize, and they didn't include a note with the request, just ignore them. There's also a reason you can include a note when you send a friend reuqest. If they're not using that feature, that's their own fault.

Isn't they removed 'note' thing to kill OQ addon in WoD?

If you are b.net friends you can tell whoever they are on?