Hi, you can side load books on any Amazon paperwhite/e-ink version. It is as easy as plugging your kindle to your computer as you would a flashdrive, click on your kindle device, and place the correct formatted books into the "documents" folder that you will find inside your kindle.
I don't have the 2nd gen paperwhite, but I do have the 3rd paperwhite gen 2015, In fact, I got it yesterday. It is supposed to have a new 300 ppi resolution (the 2nd gen has 212 ppi). I have tinkered with the 2nd gen in the stores and to be honest I don't see any significant difference with performance nor contrast (Most of the paperwhites and voyage versions seem to have had bugs and screen color issues anyway, I will get to that below). You can get either the 2nd or 3rd gen, either one imo is like buying from a box of chocolate. Sadly. If you don't mind spending the money maybe you could consider the Voyage as well.
Anyway, I am not pleased with my paperwhite 3 due to the poor color contrast issues. My device is presenting a yellowish hue (some paperwhites regardless of version are either whiter, yellowish or blueish). I feel due to my yellowish hue, the text is not as vibrant on my device regardless of light settings. I still own the kindle keyboard, and the original Kindle Touch, and I see the text with more vibrancy on the kindle keyboard (this should not be). I am so disappointed, I was hoping and needed for my text to pop out.
Read the middle reviews, over the few years there seems to be an ongoing issue with some of the kindle e-inks due to the front lit color disparities. Amazon has yet to redeem themselves and win back the confidence of their loyal e-ink customers. But I do not want to discourage you from the e-ink reader experience as they are much better for your eyes over the tablets' LCD backlits (Kinde fires, ipads etc), avoid heavy reading on tablets. Best of Luck.