Most phones you can click 'OK' when you take the picture. Otherwise, click options when you open the picture, and then send via text message. However some pictures (i.e. downloaded ones) will have a...
You can send a picture message on iPhone 3G and iPhone 3GS but they must be on the latest firmware. However you can't send picture messages on the original iPhone even if you have upgraded to the new...
It depends on the phone. for instance, on the reality, you press view now and then press reply. That's the way it is on most phones. I hope that helps! :)