Right now it seems that you have to enter each tag separately and hit the add icon. In future versions, can we enter all the tags at once separated by coma? right now that does not seem to work if you do that.

This is a good idea. I would suggest to open a ticket about that.

I didn't know there was a ticketing system. Where is it?

It's here on GitHub
https://github.com/zenphoto/zenphoto/issues
You will have to create an account first.