Hello Welcome to HCM..
I thank you for posting your query here and I'm definitely going to help you out.
I being a surgeon, we encounter so many such cases day in and day out.
I read your question completely and have understood it well enough.
I will analyze all your points and provide necessary explanation.
1. Basically umbilical
Sinus Is abnormal tract present which ends blindly without connecting to any of the internal organs like stomach, intestine etc
2. Observation is good enough in some patients for healing..
But few people need surgery.
3. In surgery, the Sinus tract is excised and associated corrections done.
4. It's not a major one, but needs around 2 days hospitalization
Can be done as a day care too in advanced centers.
5. Recovery time will be 2 weeks..
Hope this helps you, in case you need further assistance, get to direct query to my profile Dr.Manjunath Metri.
Will be happy to help you..
Take care.