Disciplining yourself to write down ALL the out-of-bounds words and pause and point to them is very, very useful for getting yourself to go slower. Remember that it only feels like it takes forever to write them out to YOU. The students don't feel like it's that long a time.
So, there are three issues:
a) What words will you need? Anticipate as much as possible. Use pre-made word cards -- pass out questionnaires at the beginning of the year asking for favorite actors, singers, colors, foods, places, as many as you can think of. Copy them onto those little flashcard cards you can get in the stationary store, and keep them in ziplock bags or some sort of container, divided up by type. So when you need a person/character, just reach into the Characters container and pull one out -- voila! -- complete with Chinese characters, Pinyin, zhuyin and English. Then, appoint a Class Secretary for the day whose job it is to neatly and quickly copy that information onto the board in very large clear writing. Use a kid who is either too itchy to do well, or who is going to get bored with a "special job" in honor of his/her advanced status in English.
b) Can you write the words you already know in Chinese? If you are just forgetting the characters (like, ahem, me... :aiyo: ) I actually have a solution for you, or rather it's at the printer now. More on this when they arrive...
c) If you don't know the word in Chinese and need it on the fly, you'll need to have a good electronic dictionary (Pleco on an iPod, iPhone, or Android is my recommendation) to provide the information. Use this opportunity to model for students that a good language learner keeps learning all his life, and isn't afraid to look things up.
I think you're right about avoiding the co-teacher if possible, assuming that s/he isn't into CI.
This will happen naturally when you go over to all-CI input, since the use of questions is so frequent that kids can't help but acquire the question forms.
Question words -- YES. I even sell question word posters pre-made for teachers of Chinese. But you can easily make them yourself, or, depending on the numbers in your class, have the kids make them for you on some day that you feel less than ambitious. I would have the English in large type and the Chinese characters underneath in smaller type but still visible from all the seats in the room. I usually use a single sheet of A4 paper for one question word. These are left up all the time.
I used to have the colors up on the wall in my Chinese classroom. You could do this with any set of words you were working on slowly -- using as detail in input, without being the main focus of the lesson. It saves you having to write them all the time. I also put up a few things like tall/short, etc. for my beginners, to help provide instantly pause-and-pointable details about characters in stories.
I had a sign on the wall for "May I use the restroom?" since this was such a popular request. I didn't make them say it if they didn't want to, but I would say it. "Oh, you want to go to the restroom? Okay. You go to the restroom now." Or whatever. They will acquire it, like anything else.
The rule in a TPRS classroom is that there is no native language DURING INPUT TIME. There are times that may be deemed "non-input", and at that time if there's a shared native language, people use it. It's unnatural to force non-fluent people to use the target language "spontaneously" especially when it exceeds the bounds of what they've acquired. One of the best classroom managers and a TPRS teacher has a construction-paper thing on the wall with a "hand", like a clock hand, on it. One side says "Francais" and the other "English". When the "hand" is moved to point to French, only French is allowed.
Practice circling. Circle everything you can think of. Get someone to count your repetitions of specific items. Circling is the heart of TPRS and if you can circle unconsciously, varying the order, getting your comprehension checks in there and not speeding up while doing it, you'll be much happier.
It sounds like you're doing a great job starting out with TPRS! Those are the main things to be watching for. If you have kids who are more advanced or who need "jobs", get them to occasionally count your repetitions of a certain word, or count how many questions you ask in a minute. All of these things are benchmarks that can show you your own progress as you move along in CI instruction.