If that dilution is a concern, just fry the rice w/ your sauces first, take them out and then fry all your meat and veggies and add your rice in again. There are two different ways to do the egg, cook it separate, like scrambled eggs then add, or add to your rice and stir fry all at once. I like the latter myself. That's how most Chinese places do it.
I honestly don't know about the chilies, since I don't use that myself, I would just suggest trying chili oil. Those can be pretty hot. If you're looking for really hot, only use chili oil to stir fry, then you wont need any chilies.
As for the mushrooms, that's so hard to say. It really depends on what you like, since we're tossing old school out the door.
I personally like wood ear, this is because it's kinda crunchy and has a nice texture. If you're hesitant to try something new, just put what you feel comfortable with. Let us know how it turns out! If you got a camera, take pics! I love looking at food pictures!