"Is there a way to lower the audio levels for sources other than the talent during a production without manually lowering them?"
Yes, this touches on the Talk and Solo features. For input two, the control group includes Talk and Solo switches. Talk is an abbreviation of “Talk Over”. Enabling Talk causes the level for all other audio sources to drop off by 20dB, allowing the ‘talk source’ to dominate (very useful for public address announcements). Enabling Solo for a source sends its (post-fader) sound to the Headphones output. This will also remove all non-soloed sources from that output. Solo (i.e., all currently soloed sources) is also an optional source for the Stream output.