Did you find the cart? Search south east of the Dwarven Bread inn.
Tingalf/Marcus/wagon quest (SPOILER)
Are you having difficulty killing the trolls? Lightning works well. As a warrior I just moved back towards the entrance after the conversation ended, so I could take them on a few at a time. The first time I tried the cave (before getting the quest or clearing much of the area around Aleroth) I was not strong enough.
Besides getting experience, there is nothing to do in the brothel.
There is a house on the western side of the quarantine area, with a back door on the outside. Talk to Lain(?) in the poor section (the guy who referred you to the thieves' guild in Verdistis) to get the key, or use Lockpick.
