Thanks for your very helpful advice.
I looked at Wiki and can see it's going to be very useful. It would have taken weeks for me to find it on my own. The links on this site aren't as helpful as they might be for a newbie e.g. "user cp" doesn't construe its purpose very well so consequently discovery is a bit of a long process
The posts on this site have made me realise that there is a minefield of issues that I need to consider. The format I produce my ebooks in is a major one. I intend to use drm as I'll be selling ebooks that teach English in China. There could be a billion copies being read within a few months of my first sale if I don't protect my book. I can see however that I'll be restricting sales if I don't allow users to purchase the format they need.
This site will help me to make a better decision about things like that.