I would agree with your assessment that there isn't a definitive answer on 1 and 2. If you're not comfortable doing them I would recommend that you go with 4. Unfortunately your desire to not be tied to a DRM scheme that has no future would drive you to option 2. Since you still have a US mailing address and credit card though I think you're in much better position to stick with the Sony.
None of us can predict the future although we all like to pretend.
The announced Borders/Sony store might give you additional future options and who knows Sony might start selling in your country within the next 4 months.
My personal opinion is that your option 2 is as likely to go away in the future as the Mobipocket format. To further complicate it I believe that options 2 & 3 would also be available for option 4.
Sorry I can't be more help other then to say I had the same decisions and went with the Cybook.