Welcome to Chi People. Thank you so much for rescuing her. Give her time with the shyness, let her come to you, lots of treats at first. Try sitting on the ground, to a small dog, we are giants and until they trust you, a reaching hand could mean hurt to her. For pottying, start by taking her outside every hour or so and everytime she pees or poos, you make like it's the most wonderful thing in the world. Praise and give a small treat. It will take a little time for it to click, but she will get it. All messes in the house ignore as much as you can, maybe make a little disappointed sound, and clean very well with an enyme cleaner to get the smell out so she doesn't go back there again. Don't give her a lot of freedom in the house until she is more reliable so she can't hide and do her business. Are you training her for outside or to pee pads? I use both, but a lot of people use one or the other. Do you have a crate or pen for her? If you work, where will she be and for how long? If you work long hours, I would suggest either an x-pen or locking her in the bathroom with a pee pad, toys, a bed or blankets, food and water. Most of my chis all sleep on my bed at night, I have a few that prefer to sleep in a crate or a dog bed in my bedroom. Do you free feed or do meals? And what food do you feed? Try to pick the best 4 to 5 star brand of kibble you can afford. Here is a great website that breaks down the value of the different kibble.
Dog Food Analysis - Reviews of kibble
A lot on here go grain-free or RAW, you could also look into that. That all I can think of off the top of my head right now, I need my morning cuppa coffee before I can come up with anything more. If you have ANY questions, throw them out and we have a bunch of helpful people here that will be glad to give stories on what worked for them.