Hi, It' a jailbreak not a swiss army knife.
The JB lets you install other applications - aside from the amazon approved flavours.
Those applications could allow you to do these other things you listed.
PDF: Buf if I am honest PDF support is terrible,
EPUB + stufff: Hacked up reader is paperwhite ready I think,
RTL: meh probably
The Paperwhite is far too new to give you a big "Yes" and the Jailbreak will only allow these "future" things to run. not anything else.
https://wiki.mobileread.com/wiki/K5_Index You could look there (much of the stuff will one day run, or does already)
HTH