Sony is much sturdier than Cybook thanks to its aluminium casing. It takes any SD cards, Kingston or otherwise, though naturally brand name cards are usually better in reliability and performance. Transcend and Scandisk seem to be pretty well-known so they should be fine. Also, the card doesn't have to be 2GB in size (I wonder what gave you that impression).
As for PDFs, it largely depends on what kind of books you have. If it's mostly text, Sony's PDF reflow should work pretty well. Otherwise, PDFLRF might help. You can check how it might look on the Reader by downloading
eBook Library and opening your books in it. The program simulates Reader's screen pretty closely (except for contrast and actual screen size).
B&H is a good shop and I would recommend it over eBay unless you found a much better deal there.
Sony does have warranty only in US but from my experience it's not very likely you'll need to make use of it. If you do, you can still send the device to US for repairs but it's best if you have some friends in US who can receive the unit back and then send to you. Some people mentioned that the repair center can send the device overseas on request, but it will be the cheapest option without insurance.