Okay, I'm pretty new to InfoPath so to help myself (and anyone willing to help me) I thought I'd go through the process I'm taking with this proof of concept. This goal is to make this work and then apply to some existing forms later.
My goal is pretty simple: Use an InfoPath form to populate one list in SharePoint (Offering Details List). One of the fields in the InfoPath form will be populated with data pulled from another list (Refresh Dates List).

I have two lists in SharePoint that are relevant (Offering Details & Refresh Dates):

I started a fresh instance of InfoPath and started designing my form. This POC will have 2 fields -- Title and Dates. I added a Text Field and named it "Title". I then added a Multiple-Selection List Box (don't know if this is the best option for what I'm trying to do). I then went through the process to get it to retrieve data from the Refresh Dates list.





Here's what the Preview looks like. It is pulling the dates (which I'd like to format differently, but first things first):

I then published the form to a new library (New Offering):





The Title field is the next thing I need to address but have struggled with.