PW2 Should I buy new KPW2 with 5.6.1.0.6??

Hello,
I want to buy a new KPW2, and I think it will be shipped with the latest firmware 5.6.1.0.6.
So, it will not be able to be jailbreak-ed, (I don't think I will do the serial port method).

1- can I install Duokan in the latest firmware without jailbreaking??

2- can I edit the margins (especially for PDFs) on the device?
or I need to do that via PC?

3- Does it support RTL sideloaded books (Arabic)?

4- Whats the compatibility with calibre (in converting books to mobi or azw3 and sending them to the device)?

thanks in advance