Most synagogues will provide you with basic information on requirements and honors. Some logistical information might not be covered...
1. Usually all males are required or requested to wear a kippah. Are they required to wear a tallit?
2. If they have an honor such as opening or closing The Ark, saying a blessing (aliyah) before/after a Torah reading, carrying/dressing The Torah, or other honor, are they required to wear a tallit along with a kippah?
3. What honors are non-Jews welcomed to have?
4. Will there be a scheduled time for rehearsal?
5. Will there be a scheduled time for portraits? Are photos or video allowed during the service?
6. If Grandparents are invited to stand or otherwise participate in saying the Shehecheyanu prayer, does this include non-Jewish Grandparents?
7. Is there a requirement to purchase flowers or sponsor a kiddush/oneg?
I guess I'll add to the list as we go! Please feel free to leave your own questions as a comment below and I will add them to the list. Thank you!