Yes. I would like to be able to download the books as a pdf, doc or txt external to the kindle reader.
Discussion
Can only do it if the books you purchased are DRM free, which is unlikely. Beyond that you're getting into piracy territory. You didn't buy the book, you bought a license to read it on your Kindle.
Would you know how I can identify if they are drm?
Not really. I looked it up and tried the advised process of checking the Amazon store page for products I purchased but could not find details indicating DRM status on any of them. The large majority of titles purchased on Amazon would unfortunately be locked down though.