Wash her as needed, we sometimes wash him every 3-4 days if he goes outside to play and gets dirty in the process, but if he's clean, he doesn't get a wash. I think it's been at least two weeks since his last one, and he still smells fine. Make sure you don't get water in their nose, they HATE that!
For the crusties under their eyes, you just need to get a fine-tooth comb. I'll try to take a picture when I get home to show ya what it looks like, but I'm sure it's available at any pet store. What you do is just brush that from the eye area down, and it gets rid of the eye boogers really well. Your Yorkie will have to get used to it, but I think she will eventually. Also, if you don't have the comb on you, you can just dab a piece of wet cloth or napkin and clean the area for her.
To get her used to you touching her face, you can try to gently pet her head a lot to get her used to your touch. Then work your way down, and try rubbing the area between her eyes, my Yoda loves it and if he's laying down when I do this, he usually takes a little nap.
After that, you can try to gently rub the side of her face, etc... I think this kind of interaction works best while they are laying on their back, or if you 'get down' with them on the floor and play with them there. Hope that made sense!