Well, I can see how writing is one thing that you fell you can do that doesn't hurt too much! I'm checking into the Kindle thing, but I don't have much time for the extra curricular right now. I'm already behind on a writing promise that I need to push some other things aside for. I've somehow lost the book I am writing a review for, and I JUST had it. It's hard to write a review without having the source right there for accuracy.
From what I can see, Kindle expects you to upload your story from any one of multiple source files types. One that they recommend is .doc or .docx. That is one of their preferred formats. They then break each one down into it's preferred formatting. There isn't much formatting necessary on any of them, so I can't see how it's going to cause a problem unless your book as images. They seem to be mentioned as the biggest source of trouble.
Otherwise it seems spacing and font size is pretty standard. I'd look into that closely and make sure you match it. And, even though openoffice and libreoffice are "compatible" with Word files, you may consider trying a plain text or RTF format just for comparison. Their converter might be looking for specific format indicators that don't come across from openoffice.