You will never know everything as a CFI. Know where to find it. Don't be afraid of saying "I don't know" to a student but make sure to follow it with "let's look it up".
If I can suggest anything, it would be know the FAR/AIM as well as you can. I read 20 pages per night. Got to know the regs better and never had a problem sleeping.
Spins are fun. Don't worry about it. I was a little apprehensive about them as well but when it started I fell back on my training and what do you know? It worked. Hitting a student to get them off the controls when they freeze and put you in a spin is scary. Doing them for training/fun is not.