Maybe everyone knows this already since it came out when I was away from the forums, but I searched the Premiere Pro forums for the word "spreadsheet" and got no related results, so here goes....
There is a way to type all of your information for lower thirds, or titles of any kind for that matter, including the kind of sub titles that are actually on the video itself, into a spreadsheet and using variables, create as many Photoshop PSD files to be imported into Premiere Pro as you wish.
It is brilliant. Simply brilliant.
Download the sample project and the PDF of the instructions. They ask for your name and e-mail address so that they can lock the PDF to one person (another good trick) to avoid people sharing. They want you to see the info about the book. But this chapter if free. And brilliant. Simply brilliant. But I guess I said that already.
http://premierepro.net/editing/spreadsheets-to-lower-thirds/