All your purchases of e-books and other e-stuff from Amazon for the Kindle will still be available for download from them to a new Kindle. All you have to do is register the new one at Amazon.

Other e-stuff you got from other sources like pdf's that you have on the old Kindle will have to be saved to a PC other other device and then transferred to the new one.
.

I recommend asking AMAZON directly, via their website, perhaps. My understanding is that they are the makers of Kindles and could likely, correctly provide the answer you seek.
Happy Kindle-ing!