To get the lizard teleporter scroll, you must heal both soldiers in Aleroth, and talk to Goemoe about the scroll before he moves to the council hall.
If you got some experience points as well as the level of Restoration from Mardanius, then the quest is complete, and is sounds like there was just a glitch with the quest log where it didn't get marked off as done.
For the Duke's assassin quest, did you try just going to the house yourself? The assassin drops a letter that you can bring to Ralph to complete the quest, so getting help isn't necessary (the quest experience is the same either way; if you get help you just miss the experience defeating the assassin).
A belated welcome to the forum.