We have a male 9 month old 'Turkish Angora' kitten. He is very aggressive, yowling all day, doesn't want anyone to be closer to him; when anyone goes closer to him or touch him he leaves the place where he is sitting. We visited vet and another person told us that this can be fixed by neutering, as there is no female cat in our house. Is neutering the right choice? Is it the right time? We are really annoyed by his yowling.
Yes, a cat will normally calm down after neutering, and neutering is a normal thing to do for every responsible cat owner. It will keep your cat from getting into fights with other cats.
My question is, why did you not get this done when you last visited the vet for vaccinations and health check?
Neutering is done in about 15 minutes at the vet and it saves you from a lot of trouble, like spraying-fighting-screaming.
A neutered cat have a tendency to gain some weight, so you will possibly need to change the food to one formulated for neutered/spayed cats; most major food brands have this.
However, a 9 month old cat will normally not need special food until it gets older.