- No.
- No. Kind of. See KOReader.
- No. (usually)
You can use
calibre to convert from PDF to mobi/azw3, although as PDF is a lousy input format, YMMV.
Master index for Kindle hacks and suchlike is here:
https://www.mobileread.com/forums/sho...d.php?t=180113
You have the Kindle 4 non-Touch, the Kindle 5 is the PW1/PW2/Fire