How long will the incision be, and what can I expect in terms of scarring?

Depends. Length of the incision depends on the surgery. Be confident that surgeons will make the length as long as necessary to perform their surgery. Scarring will also depend on the surgery procedure, location of surgery, skill of the surgeon, type of sutures (stitches) used, infection or other complications and the patient's ability to form scar tissue. Best to discuss these issues with your surgeon.
Using this site. You can get the most out of this site when you provide background information on your problem & ask a clear question that reflects on the info you submitted. We don't know if your question is about lancing a zit, or having heart surgery.You are welcome to start over.
It depends. What is the surgery you are getting? We can't answer the question without that information!