usage - What does とな mean (and how do I use it)?

I came across this on Twitter, it seems to be mostly a question but sometimes an exclamation. Is it とは, or maybe とか? How do you use it? My dictionary has a とな as word that come at the end of a sentence to get confirmation. Is this the same?

画像も貼らずにスレたてとな？
今日は次第に雨とな。

千葉東方沖震度4とな？
むっちゃんがイケメン店員とな(￣□￣)!?

The avatars of people using it are overwhelmingly cute. Is this a cute word.

Answer

As YOU wrote, とな in these examples is a combination of the particle と signifying quotation and the particle な signifies that the speaker wants reply or agreement or wants to make sure. I think that とな in this meaning is rare in the modern Japanese except as an Internet slang or possibly in some dialects.

“画像も貼らずにスレ立てとな!?” is a set phrase used in some Internet forums including 2channel. It means something similar to “You started a new thread (in the forum) without even including a single image in it? Seriously?” I guess that many of the uses of “とな!?” (or “とな?”) are inspired by this set phrase.