bookmarks-> imported bookmarks also displays old speed dials, but these seem to be from a far earlier sync, my guess would be from about 2-3 years back.
Those are the ones imported from other browsers in your computer. By default Opera imports some data from the default browser during the installation.
therwise my current bookmarks/speeddials are only available from the link you provided.
Then it seems that something is wrong with synchronisation in your Opera.
Have you tried logging out from Sync and then login again?
Do you see anything under Bookmarks and Bookmarks > Other Speed Dial?
in that link, the right click context menu gives me the option to add a folder to my speeddial
Nope, this is an option to add the page you are on to your speed dial.
Also, the link you provided gives me a choice of two machines, one being my old system with its bookmarks, one being the new one
Under bookmarks? Which version of Opera were you using before?