1) Other than the battery indicator not always being accurate (it will show two bars then suddenly a low battery warning will come up) then no, no issues or crashes or hangups.
2) Not much different. I have a Kindle where I do most of my reading, and an iPad if I want big-screen PDFs. The Libre is mostly for fanfic, personal content, magazine articles and things like that. I was hoping to funnel it to my dad at some point, but he wanted the Kobo, against my advice, because it's pretty...
3) Haven't tried. I only use a dictionary when I read in French (which is one of two reasons I upgraded my Sony to a Kindle) so I was not interested in this feature on the Libre.