How to concatenate a Date field with another field while keeping the desired date format, and how to handle multiple picklist values using a ternary operator.

Resolution:

  1. When concatenating, the Date field must be formatted explicitly to avoid output changing to a long date format.
    Example: {!Check Date}.format("MM/dd/yyyy") + " & " + {!Check Number}

  2. To check multiple picklist values in a ternary condition, use the OR operator:
    Example:
    ({!Payment Method} == "Check" || {!Payment Method} == "Money Order") ? {!Check Date}.format("MM/dd/yyyy") + " & " + {!Check Number} : " "