When you create a bookmark from the heart menu you can pick the thumbnail at the time of creation. So you will also be able to set whether it is a bookmark or a speed dial entry from the heart menu. If you use another method to create a bookmark or speed dial entry, such as the right click menu, you cannot pick the thumbnail. You can edit it later view the heart menu if you wish.
Partner Speed Dials will preset images for all the pages of similar domain (e.g. twitter.com is a partner entry, if you add twitter.com/user it'll use the partner logo instead of thumbnail), there's no option or fix for that as of now. Unless you customize manually.
Stash is an alternative, but it has a very different usage pattern.
I see. The deal is that i prefer opera so even houswife or kid can use it easily. Okay we will wait till they implement this feature. Maybe.