I think brunch sounds great.
Waters Edge is lovely. I was there for a conference last year and they did a beautiful job.
I like the brunch idea. If the majority of your guests would be negatively affected by a Sunday brunch, then perhaps think about Saturday. Personally, I'd pick another time to go to my own church or just skip it that week. If it's just one or two people that wouldn't come because of church obligations, then I think you have to plan for the majority, not the minority.
As far as alcohol...I wouldn't expect a full bar at a brunch. I'd expect coffee, tea, juice, water, soft drinks, Bloody Marys and Mimosas. Champagne for the toast. But that's just me. We did a brunch anniversary party for my parents 15 years ago and that's what we served as far as alcohol was concerned.