... and with another 24 hours under my belt I'm getting along much better than before, EPUB does indeed seem to be the way to go (with a few reservations at this stage) but has any single medium ever thrown up so many different incompatible and obscure formats?!?!
And having searched a bit further around the Interweb I'm still trying to get my head around the concept of ebook reader software that requires a computer to run it. If I wanted to read something I wouldn't take a computer with me, I'd take a ..., oh what did we call them all these years ago... , oh, I remember, 'book'.
So far I've only tackled about 6 books. I don't seem to be able to get a sans serif font in the PRS-505 when using EPUB: everything I start from ends up as the same serif. No big deal, it's quite readable, and at least italics, bolds, page ends, paragraphs etc are observed.
So I'll tinker some more and then come back with some properly formulated and structured questions. Who knows, I may even find time to do some reading
Thanks again to all who responded, and especially to Kovid - excellent software, well supported, filling a real need.
Ken