Welcome to YT!! I pretty much agree with what everyone else said. A few of my experiences have been different. I do have a preference for boys because in my experience, they are sweeter and adore their moms! (I'm assuming your a girl)
That can also be seen as a negative, since not everyone wants a dog that is clingy and wants to be with you AT ALL TIMES!!! Girl dogs are sweet too, on their terms and when they want. (Again, this is my experience) Boys and girls mark depending on their personality. My boy do is very interested in marking, not as much as some girl dogs that I've met!
Most importantly, each dog is truly an individual. They each have their own personalities which is what makes them so special. My baby boy Kaji loves other digs, big, small, he loves them all. He's terrified of men and kids, loves us girls.
and he's calm yet playful. He doesn't bark, he just chooses not to. So he's this hyper little dog and calm at the same time. It's hard to explain. He's the perfect balance.
Anyway, good luck on your search for a yorkie!
PS to answer your potty question, as a fully pad trained adult, Kaji has access to the pad 24/7. He goes when he needs to. Some days he goes 3-4 times. Other days just once. He doesn't have a schedule.