Quests and Achievement Questions

[Csimbi]

Here are two screenshots.
One's the entrance to the cellar (for the barrel of herring). The minimap and the surroundings should give you an idea about which village this is If you tap 'm' to open the map and consider the shape of the landscape a lizard, this is the village at the lizard's back fin (on the East side of the map). The entrance is that trapdoor with the blue glow (marked it with red).

The other screenshot shows the hero standing at the spot where you get the notification about the bear tracks. If you fly to the point where the arrow points, it won't trigger. Walk through the bridge towards the arrow. The bears will ambush you from behind (so you can't escape unless you quickly tap 'f' to fly).

As for the third, I am playing on Impossible and I have already 89/100.
You can get extra crystals in battles and by digging for treasure, as well as by destroying items (the higher your skill, the better items you can destroy and the more crystals you get).

Hope it helps.