Originally Posted by rglk
But then, how does one know beforehand whether a given Kindle book is Topaz-encrypted?
Look at the Product Details section of the Amazon description page. If it has only a Print Length and no accompanying File Size, then it's a Topaz book. If it has also/only a File Size, then it's Mobi.
Also, for step 2), it sounds like the cruft you have to strip out is auto-generated and probably fairly uniform, so if you have any scripting skills, you might be able to whip up an auto-converter to make your life easier.
Hope this helps, and welcome to MobileRead!