Does the "Exhibit A" section at the bottom of the MPL need to be filled out within the license text itself? Is just including the "boiler-plate" license comment from http://www.mozilla.org/MPL/boilerplate-1.1/ in all source files and a verbatim copy of the MPL sufficient to cover a project?

There are blanks within the "Exhibit A" section that look like they should be filled out, yet it doesn't make sense that the license text should need to be modified in addition to the boiler-plate license comment.

Yes, the blanks need to be filled in, or rather, should be filled in. At a minimum, it identifies the original copyright holder. The MPL relies on the original copyright holder's rights covering the work to grant the license.

In other words, if there is no copyright holder, there is no one with the authority to grant license(s) -- the work is either not theirs or the work is in the public domain.

As for whether copy-pasting is sufficient to cover the project--that, I can't answer. If I were in your shoes, I would send an email to the mozilla foundation asking for clarification or instructions on putting the license in practice.