To answer your questions;
Colors vary, some are different, some are the same.
No, not all Yorkie's are 3.5 pounds, I have a 4 month old little guy & he's 4 pounds.
Barking, well Bentley barks at everything he sees, he's still a pup, and he's crazy with a bunch of energy that never dies down. He has been getting better though.
House breaking, good question. Every Yorkie is different, one will learn faster than the other. It takes a lot of time and patience.
They all come in different sizes, colors, looks, personalities, coats, 3lbs or 8lbs, black or brown, barking or not. I am almost positive you will
love your little furbaby the way they are! That makes it the fun part, they seem so alike but yet so different.
As to where to find a Yorkie, try searching for breeders in your area.
I hope you find your dream furbaby!
Here's a picture of mine...
Good luck!