The Pirc, KID, and KIA all have similar structures. If you become expert at one, will you become expert at all three?

I would say not because there are different lines to deal with in each three, however if you are an expert in one, I would think that you would be able to play the other two decently.

no, differnt continuations and different motives.

No, especially the KIA, because you have an extra tempo. You'll be familiar with the others, but not as expert as you are on one. The Pirc has many traps to memorize, so you won't be as good in it as you are in the KIA.

In my opinion, the Pirc is weaker than the KID.  Perhaps a better way to phrase that would be to say that the Pirc is more difficult to play well?  You get my point regardless.

The KIA is an opening system for white so I don't feel it's valid to lump it in with the Pirc/KID.

I understand that the KIA is an opening system, and so you are dealing with different move orders, the extra tempo as white etc. When I first started to study openings, I thought the Pirc was just some fancy KID against e4, but now I see that you have to take into account other factors that make e4 different from d4. I would like to thank you all for your help in making me study these openings more deeply. There is more under the surface than just the similar structures you see at first glance. Thanks again.

i use all 3. and i am equally bad at all of them.

will anyone post diagrams in this forum so I can see what they are?

Now you can understand my confusion wnen I first saw these diagrams

I agree with you about the Starting Out series of books. I own a few and I think they give a wonderful basic introduction to the chess openings. I have the one on the King's Indian Attack. I plan to get Watson's books soon. Thank you for your help on this subject.