Hello Noah,
like Jakob told don't open more threads, you can ask you questions here, and improve a design as you go along but keep the project all inside one thread only.
You are 16 years old it's great you are doing mic preamp, I'm sure we all will try to help you but it's hard when you ask the same questions in 8 different threads.
So first thing, keep to this thread only.
Second thing, you're basing your design on a datasheet, thats great. I guarantee you that if you build a circuit exactly like it is in the datasheet it will work, so you dont need to be insecure about that, just do it.
If a circuit can be improved from the datasheet example? well it depends on the needs, but sure.
Read the explanations in the datasheet and if you have doubts after the reading ask questions.
third, where are you located?
that can be helpful to know in order to recommend you places to buy stuff
Do you have a already a PSU board?
if not send me a PM with your address and I will send you an SSL 9K PSU pcb that you can use for your project
forth, for Balancing output you can use the THAT Corp 1646 chip, it has built in short circuit and phantom power protection so it's quite easy and simple to use