There are not so many benefits to castrating a dog as there are to spaying a bitch. If you do decide to neuter, personally I would wait until your dog is mature, around 2 years old, as he will then have finished growing and maturing mentally. Dogs that are neutered early can exhibit 'puppy like' behaviour for their entire lives, which can be tiring for the owner. They can also become very tall and gangly, and ther eis also some evidence to show early neutering can exaccerbate any hip/joint problems that are underlying, due to the effect of neutering on the closure of the growth plates. (neutering delays the closure of the growth plates)
Neutering obviously elimates completely the risk of testicular cancer, but can increase the risk of prostate cancer, something much harder to treat. Early neutering can also increase the risk of bone cancers.
Although neutering means your dog cannot successfully mate a bitch, responsible ownership also does that, and scent marking/roaming are behaviour issues or can be controlled environmentally. (eg, better fencing, closing gates, proper training etc will prevent roaming)
With regard to breeding from your dog... unless you are prepared to show him, and do well in the ring (something very hard with a prolific breed like a lab) then it is unlikely you'd get any responsible bitch owners who wanted to use him at stud. Also, you really need ot be prepared to be as equally responsible for the puppies produced as the bitch owner, and be prepared to take them on if their owner or the bitch owner can no longer keep them. Breeding is also risky health wise to your dog. Also, your dog will probably have endorsements on his papers if his parents are from a decent breeder with show dogs themselves, which means you cannot breed from him and register the puppies unless the breeder agrees to lift those endorsements, which may well be subject to a good show career.
If you think you might want to breed/show, why not ask your puppies breeder about a ringcraft class near you? It is kin dof like atraining class, and will teach your puppy to stand and be felt all over and have his mouth lookd in by a 'judge', which, even if you decide showing isn't for you, will mean your dog will be easy for the vet to handle in the future. It si also really good to get your puppy socialised with lots of different breeds of dog of all ages in a 'safe' enviroment. (all dogs will be on leads)
I hope this helps.