[codrutoctavian]

My problem is the following:
- I have a Kindle 3 with 42 books from amazon in azw format
- I have recovered 32 books which I bought a few years ago from Sony ebook store in epub format.
- I have deDRMed my epub files and imported into Calibre
- I have also imported my azw files from Kindle into Calibre for backup (I don't want to loose these files as I almost happened with my Sony ebooks)
- I also added some pdf files to my Calibre library

Now I have the following questions:

1. Some of the azw files from Kindle where converted not in mobi format but in HTMLZ format. I cannot open these files in Calibre. What am I supposed to do with these files? All I want is to keep a backup of my amazon files.

2. Is there any way to convert all of the files to mobi format? What is the better format epub or mobi?

3. Regarding pdf, I know this is the most difficult format. I have a license for a software named DeskUNPDF for Mac. I have bought this software a few years ago exactly trying to improve the conversion of pdf to ebook readers format. So far it was not really useful. However I have tried to convert a very large pdf with multiple columns and graphics to html and it did a nice job. Is there any advantage in processing a html file? Perhaps the conversion is better from HTMP to MOBI. If so, how to do this?

4. Does it worth trying to convert the pdf files to mobi? Or should I leave them as pdf?

Thanks.