Will the PO number remain the same when I use Cancel and revise?

When you use "Cancel and Revise" your purchase order gets canceled and then will receive a new purchase order number.

When you use cancel and revise, the current Purchase Order gets canceled, and a copy is made containing the same data as the previous one that you can edit. After it is completed and resubmitted, a new Purchase order number will be assigned. 
The purchase orders will be linked together, meaning that from the comments section you can always access the old/ new purchase order.