The fair use factor doesn't care why there's a market, just that there is one, or is likely to be one, and that the use is harmful to it.
Fortunately, most eBooks I've purchased have clearly been reformatted to work well on eReaders.
Bah; I've yet to see an ebook that was decently formatted at all. So far it appears that good typography is available only in print.
There is also a "first sale" doctrine. If I go out and purchase a book and make a poor OCR of it and I then lend you both the physical book and my poor OCR simultaneously, I would probably get away with that.
Only if the making of the OCR'ed copy was legal. Fair use is a case-by-case analysis. Just because Diamond v. RIAA turned out well in 1999 doesn't mean space shifting to OCR would now. (In fact, I'd be very worried that a new round of anti spaceshifting litigation would turn out the other way)
If I bought the book, converted to a digital format, and burnt the original for heat (saving the receipt). I think I would also be okay (but I don't plan to find out in court)
Same as above. Once you have a legally made copy, it is subject to first sale. The question is whether the OCR copy is legally made.
Google Books originally lost because just *building* their digital library was ruled to be infringing. But I think they got past that on appeal.
Google Books succeeded, but then they don't lend out books.