What I think has no bearing on your problem (besides, I only read English

).
I like AZW3 because I can make a book look almost the same as on my ADE based reader.
The WiFi mostly stays off on both the K's in this household, we side load. ( I even used to leave the Access point off until I got a Tablet and a WiFi enabled phone. Color me paranoid, but business has enough hooks set that I don't need a solid line in). I am too cheap to hang at the local Starbucks using their
free WiFi. I load before I go with more books than I could ever read in Days, let alone a few hours