Hi Carlos,
First off, a Sept start for your project works well for me. Next, I'd like you to know that "alternative" therapies are a subject of immense interest to me. And, finally, writing's a passion... I write for the sheer joy of it.
I have "ghost"-written six books in the past three months and apart from the fee, there has been no other consideration, monetary or otherwise.
Writing for a North American audience is something I enjoy most; after all, English has been made so much colorful thanks to the eclectic ethnic melting pot that the USA and Canada are. Other users of English tend to be a little staid, if you don't mind my saying so.
Do let me know how you wish to take this forward in the days ahead.
Best wishes.
Prasad
SLN FastTrack