I’d just fill the gouge with a mixture of sawdust and glue and then surface — why remove more material than is necessary?
For leveling see: Wasteboard Plans with threads
To work up feeds and speeds see: https://shapeokoenthusiasts.gitbook.io/shapeoko-cnc-a-to-z/feeds-and-speeds-basics and Origin/consistency of chipload recommendations and #MaterialMonday on YouTube