I have a gorgeous dog (terrier breed) he is 14 weeks old and I'm just interested in opinions about breeding him in the future. The pros and cons if any for the dog and for us too. He is pedigree with a very good parentage.

Have a look here first :-
http://www.champdogsforum.co.uk/board/topic/55104.html

In the main bitch owners will be looking to breed the best they can (if they are doing things properly) so will be looking to use the best available dogs, that they have seen, is a mature exceptional dog, and hopefully have already produced good puppies.

A dog has to start somewhere but people are not going to use an unknown quantity, so he would have to do well at shows or in the working arena to make people want to use him.

14 weeks is really too young to plan anything as you don't know how he will turn out. Show him and/ or work him and if he does well, then have the relevant health tests done and if he's good you may be asked by bitch owners if they can use him. And bear in mind some male dogs do change their character after having been used for breeding, and may start marking indoors as well.

Is this pup a pet, living indoors?

Because I own stud dogs and would ask you to think about him cocking his leg indoors.  Once a dog has mated a bitch,, he will want another, and another!  He will be much better off never having the experience.  Honestly.