Query on ebooks for law firm (and other) marketing

Over the years, I have ghostwritten more than 15 comprehensive books on a wide range of legal and business subjects.  I recently persuaded a new client to go the ebook (rather than hard copy) route.  She liked the idea -- and now I must "walk the talk" by familiarizing myself with the process, including ebook compiler software.  Based on preliminary research, it looks like folks write in Word, transfer to PDF and then upload to a compiler.  Is this correct?  Any recommendations on process as well as ebook compiler software would be welcome.  Is there any software that lets you compose and publish in the same package?