While reviewing Sacred at fileplanet, I found a patch called Sacred Plus Expansion, that is reported to provide a boad load of additional features and quests. It is possible to patch the game that I down loaded from GOG?

Sacred GOLD includes Sacred PLUS :)
PLUS was a free mini expansion for the original game, later re-released as the main product before the full expansion: Underworld.

Which I should also add is included in the package available on GOG.