Hi vickivanv !! thanks so much for stopping by to let us know what's going on ! we're always really happy to talk to writers, publishers, and everyone involved in the book-creating process, particularly when they are so ebook-friendly like yourself !
it's great to hear that you are pushing for ebooks of the whole series and that the publisher is interested in doing that. i've not read these books yet but i love mysteries (including sherlock holmes, of course) and all i've heard about laurie king has made me really look forward to diving in ! but i've been putting it off because i didn't want to start a series if i couldn't get all the books, so i thought i would wait a bit... i'm really happy to see i won't have to wait too long.
(that is, if these books will be available outside of the kindle store ; i can't shop there, as i don't have a kindle / live in the US).
a lot of people have replied to your questions and given you some info but i'll add my voice as well.
with regard to your format questions, i would strongly encourage you to make an epub first (this can be made from a clean (x)html file) ; epub is the new industry standard format being adopted by more and more publishers (as gwynevans mentioned) so it's a good idea to learn about that format now. one of the advantages of starting with epub is that it can be read natively by more and more devices, but can also be easily converted to other popular formats such as mobipocket, so you can easily make everyone happy : if you offer drm-free epub and mobipocket, you should make pretty much everybody happy, since those 2 formats together cover almost all devices, and can be converted for the few devices they aren't supported by.
take a look in our epub forum to learn about this format, and don't hesitate to ask questions ! we've got lots of friendly experts around here who will be happy to help.
if you (or the publisher) are feeling a bit intimidated by the various formats, then i agree with kacir and others that the best idea is to make a good clean html file ; this can easily be converted to any format. personally, i don't like pdf files, even formatted for a 6" screen, because they don't give nice results when you change the font size and so they're not as comfortable to read for me.
and, lastly, kacir's suggestion is very good : please do ask for help with creating ebooks here. in fact, the friendly and expert members i mentioned earlier could probably be bribed with the offer of a free ebook to create the various formats for you.
