I can understand you worry as you are stepping into the unknown with a comprehensive amount of procedures about to be commenced.
Not having had a sphinterplasty myself I cannot answer from personal experience. You may wish to post on the Urogynecology 'Ask a doctor' part of the site as well and hope you find the answers you are looking for.
I have done a search on this site and found this Drs answer also.
http://www.medhelp.org/posts/Urology/sphincteroplasty/show/1846439
There are other answers on this question on the site so try a search under sphincteroplasty as well.
With so many procedures planned ( good to get them done all at the same time ) I assume you are happy with your Urogyne and suggest you ask them also what to expect from this and any other aspect of your operation and recovery.
You are not alone, so come back to us if you need to. I hope this helps and wish you well with your operation.