You seem to be thinking this through, and that's important because no one here will do your work for you.
I've just finished a CELTA course and I found it very helpful. My advice is to concentrate on gaining a good understanding of grammar, but also read a lot of books which focus on teaching methodology (assuming your teaching experience is limited or non-existent). And try to get some voluteer teaching work if possible. But above all, good luck. If this is what you really want to do and you find a good school you will have an amazing time. I did.
Practical English Usage by Swan is a very good reference book for the CELTA course. Learning Teaching by Schrivener is also good.
A free (PDF) book can be found at this address:
It has quite a lot of useful information regarding grammar: however it is very grammar based, so you will not find anything to do with teaching.
- For Teachers