Welcome to YT!
I really don't think yorkies are any harder to train than any other pooch. You just use patience and love, and make sure you praise praise praise. Train in a positive manner, and never yell or hit.
I think most yorkies do not have to have their anal glands expressed if they are on a good quality diet. Anal glands have a fluid in them that helps lubricate the "poop chute". If the glands are working properly, the fluid comes out with the poo. If they aren't working right, sometimes the glands get overfilled and can sometimes even become impacted, infected,and even burst. You just need to keep an eye on them, and if you notice your pup is having trouble, or dragging it's bum around on the floor, they might need to have their glands expressed. The technique is pretty simple, but you should have a professional show you if you want to do it yourself. Ask your vet or your groomer.
I am unsure how I feel about yorkies with small children. Some yorkies are very tiny and can be easily injured accidentally by kids who may not be as careful with the tiny dog as we could hope. Others are cautious of kids, and wouldn't get close enough to be harmed. You would have to be very careful when you first get a pup to make sure the dog and your children are well supervised when in the same room. I have heard that some folks never let their children hold a pup unless they are sitting on the floor.
I wish you all the best!! Keep reading, do your research, and make certain you are VERY sure a yorkie fits your personal lifestyle and family situation before you get one. But I can tell you that I will never have any other kind of dog. Yorkies ROCK!!
