Hi Sidney,
In response to your “stairs clause” question, I definitely do! I don’t like asking congregation members, or members of the wedding for help and so whenever I take a wedding or gig I ask if the location is handicap accessible.
In my contract I specify this as well, in addition to stating additional cartage fee for any venue requiring x number of consecutive steps.
Make sure you stretch before and after! Nothing is worse than accidentally pulling something right before you need to play.
Katherine