Thanks for all the advice Barry, much appreciated
As far as devices go, I'm quite happy just using an e-reader app on my android tablet, I like the versatility of being able to also use facebook etc if I feel like it without going to my computer. I haven't experimented with many of the apps, as Aldiko has done all I need it to so far.
Anyway, good to know that I can go ahead and buy books from Amazon, thanks so much for all your help.
Jenny