Spark, bite and edge? That's not much of a Labrador trait, if I understand you correctly. If you wanted a tough dog, why not just get a Rottweiler or similar breed?
Either way, some dogs mark and some squat. The dog may or may not change that. Squatting dogs are not sissies and marking dogs are not tough.
As far as size, how big was his dad? He should be a similar size.
It's best to neuter when growth plates are closed, 18 months or later.