When is the right time to neuter/spay a dog?

I have heard two things. I have heard that you can spay/neuter a dog at almost 3 months or sometimes earlier. Then, I have heard that you should wait until the dog is at least 18 months old. Which is correct and why? I have always had my dogs spayed/neutered at around 5 months old. Will the dog’s life be different depending on when you spay/neuter them?

Do you think they will ever make a Dogs Life 2 for PS3?

I am personally an Xbox 360 guy but growing up I played A LOT of PS2 and Dog’s Life was my favorite game ever!

How does a dog whistle work?

There is an annoying dog that barks for hours in the middle of the night. From roughly 12 a.m. to 2-3 a.m. this dog barks non-stop. The problem is I cannot pinpoint the house because at 3 am I don’t feel like wandering the streets.

If I buy a dog whistle and blow it steadily, will the dog’s ears hurt to the point they will stop barking? The dog lives 1 street over, will it hear it?