Hondanut,
Yes, PDF is an acceptable format. The only problem I have ever had, not really a problem, is that you often need to change the page orientation from portrait to landscape for PDF documents, otherwise the font is a lot smaller than my old eyes can read.

Easy to do on the kindle, but when you make that change, it's global. Then if you want to go read something in the standard portrait format, you have to change it back. It would be nice if the Kindle 'remembered' the orientation by document.
There are a couple of ways to load PDF's to the Kindle. One is just copy them from your PC to the 'document' folder on the Kindle. The other is to send the PDF to the Amazon server and download them from there. I think the only reason to do it this way is to provide a copy in the 'archive' for your Kindle should you ever have to restore the Kindle contents from your account.
I've found a number of PDF's on a couple of photo forums I belong to. They include exposure guides, some view camera movement references and development references, pretty handy. If I find something useful on the web that is not in PDF format, I just use a tool to capture the page(s) in PDF format, then transfer them to the Kindle.
You might want to look at a program called 'Calibre' for managing things on your Kindle. Pretty handy tool, it's free, though donations are accepted if you like it, etc.