Everything seems to be working pretty well now thanks to your assistance.
Q1. You caught me. I had tried blanking the field, but for some reason didn't try 0.
Q2. That works great.
The slider age selector still wasn't working quite right (or as expected) and sometimes wouldn't display a result if the age was in the middle of an age range. I went a different direction with the way to select ages, and while it's not quite what I envisioned, it does do the job. Thanks for all your help getting it up and running.