While not a firm requirement, research experience will definately add polish to your CV. Some "top programs" either require or "strongly suggest" taking time off during your residency training for research.
Research looks good regardless of whether or not it was surgical. If research is not surgical, be prepared to address any questions about why you are going into surgery vs. your research field.
If you aren't into research, consider checking in to the programs you plan to visit so you don't waste time and money on a pointless interview.
