Do I approve of it? Not in formal or even politely written texts, but I do use it in some text messages and in some emails which are very informal to someone like my brother or best friends. As long as people know the proper words, and it's informal, it's fine. :)

In a text message or chat it's allowable (maybe), because you are limited by time and/or space. In any other context, such as emails, essays, or online comments, it makes the writer look illiterate. I could not possibly take the writer seriously. My thought is, if you have the time and space to write something properly, then write it properly.

No, I don't, and I don't do it under any circumstances.

If you are "texting" on a phone, are limited to space, and need to use short-cuts, it is fine. If you are emailing, composing a paper, or writing a letter, I think you should spell out the words.

I think if you're writing a long text message and you have a character limit that's fine, but I see it way too often. I prefer to write words out.