Hello and welcome! My name's Kat and it's good to 'meet' you and Mia. I have little Chi named Mia Zofia! =D From what you've said, she sounds right on track for where a ~9 week old puppy ought to be. As far as potty training, when you say she is crate trained, do you have a separate area with a potty pad for her to use? The concept of crate training is that dogs don't want to soil their bedding. So, in the early stages when you're first trying to establish WHERE to potty, it helps to have the pad be the exact opposite of where her bed is. This is a pic back when we used grass patches, but it'll give you the right idea.
Basically you want to create two very distinctly separate areas; one with a comfy bed, sturdy water dish, toys, etc. and the other side for the potty. This way, even when you aren't around or watching her, her own natural instinct to NOT pee/poo on her bed will help redirect her exactly where you want her to go. =D You've got the right idea catching her in the act and moving her; constant supervision is key, use a tether to tie her to you if she manages to sneak off and pee.
As far as chewies, I am not sure what you're feeding her, but raw bones are nature's toothbrush for puppies LOL. Never feed cooked bones though, which can splinter. Raw however is what their teeth are designed for, and at 9 weeks they will help her develop strong muscles in her neck and jaws. Frozen chicken feet are great for teething pups. There are of course other rubber toys but we try to stick with natural things as much as possible. Bully sticks are a favorite of many Chihuahuas here on CP! Anyway I hope that helps. I commend you for taking the time to want to raise a well rounded Chi! It helps defy the stereotype by being ambassadors for the breed to prove not all Chihuahuas are aggressive and high strung. Often they just underestimate the need for physical exercise and mental stimulation. At 9 weeks, she could definitely start some basic obedience training; if she learns most commands early on, they'll come naturally to her as an adult. Same goes with socializing; if you want to have a dog who can go everywhere with you, be friendly and love attention from strangers; it's crucial to start doing all those things *now.* The younger the better! Dogs have a window from about 6 to 12 weeks where they are learning and absorbing everything, hard-wiring their brains for how they'll respond to such things as adults. Thus, anything you want your pup to be confident in as an adult, they need to experience it (positively!!) during this time. Even the "Rule of 7's" sticky would apply well as far as introducing different types of stimuli. Whatever kind of Chihuahua you want her to be is in your hands. =) Have fun and I hope to see you around!