TSA has officially stated (via the TSA Blog) that you can take photos at the checkpoint, just not of the displays / monitors there. Blogger Bob posted the following:
We don’t prohibit public, passengers or press from photographing, videotaping, or filming at screening locations. You can take pictures at our checkpoints as long as you’re not interfering with the screening process or slowing things down. We also ask that you do not film or take pictures of our monitors.
All TSO officers should be wearing a name tag with their last name and their position/rank. Also, many airports the TSOs have a card with their photo and both the first and last name, so you may not need to ask them for the name. The TSA directive is below:
Nametags: Officers shall wear a TSA issued nametag. The nametag will be worn on the right side of the chest.