School:
I can recommend Harv's. Did a renewal 3 years ago, and will go back next month for the repeat. Citabria's are OK - easy to fly, hard to fly well, not too underpowered (in the winter). Both Harv & Luke are very good at what you need, good competent instructors, neither are time nor ego builders.
Rating:
2 or more considerations here:
A) Have you any akro experience? You gotta be able to do it to teach it (Mr G.B. Shaw never did any aerobating, I think). You'll have to get competent before you can start to learn to teach.
B) Have you any instructing experience? It IS much more than just showing somebody something. It is given a fairly shallow technical base, but learning how to talk & fly, how to analyze errors, and how far to let bad things develop (or not) takes practice.
Take your time, enjoy it!