All right guys, I'm trying to write up walktrough to the first act, but it's really taking quite long and I don't have the time required. What I'd like you to do is this: PM me or add here descriptions of quests - they can even be incomplete, pictures aren't necessary either, I'll just add them myself, I'm sure amazing people around here will gladly point out any mistakes - and I'll update this post. Hopefully, we'll eventually create a comprehensive walktrough. And, of course, all credit'll go where credit's due.

Anyway, this is a rough template of how should a quest walktrough look like:

Find Bishop Herbertius - quest given by father Dominicus
The quest is given by father Dominicus, who is in the Hillbrant's church, near the confession booth. Bishop Herbertius himself is located in a under the Hillbrant graveyard. There, you need to throw a [url=http://s19.postimage.org/q95otvb37/MAP2_Hillbrandt_Cemetery_Crypt.jpg]lever (SG1), which opens way to herbertius' lair. That's not all, however. When you're finished with his dialogue, you'll find that he keeps regenerating in combat - that is because you first need to destroy his heart, which is located in the right-ish part of his lair, under a secret tile. You just need to pick up the heart, right-click it, and click the destroy button. Dominicus asked you to bring back the monstruation - it's either in the secret location along with the heart, or in the nearby chest.

Find the Paladins Sword - Given by Edmond D'Arvis
The quest is given to you by Edmond D'Arvis the Master Paladin, who is located in the Norheast corner of the Hillbrandt map, outside the town proper and along the road next to his campfire. The sword can be found on the bottom level of the Iron mines being wielded by the Paladins evil doppleganger. Kill the doppleganger, loot the sword from his corpse and return it to the master paladin to complete the quest.
(added by maggotheart)

Locate the Blacksmiths Son Paul - Given by the Blacksmith
The quest is given to you by the Blacksmith in town. Paul is in a shepard's house in the Northwestern edge of Dragon's Rock. The door to the house is locked and must either be bashed or lockpicked to open it. Talk to Paul and offer to bring him home, and he joins you. Return to Hillbrandt and talk to the Blacksmith again to return Paul to him and complete the quest.
(added by maggotheart)

Find soldier Jullian - quest give by Sheriff Jacob Contemburry
Odds are before you get in to talk to the sheriff a soldier named Darmont will speak with you. He'll tell you that Jullian was courting a merchant's daughter but was rebuked by the father before disappearing. This is your cue to start another quest involving Reichmann and his erroneous belief that a thief killed his daughter. Reichmann wants the thief's head. If you want to complete that quest then skip this one until you do as finding his daughter Natalia alive fails the other quest. However if you do decide to complete the quest and kill an innocent man you'll be out a potential companion for hire (the thief literally charges you) as well as the quest to prove his innocence.
That all said this quest is easy. Jullian is located in a small building at the mining cemetery. As you enter the building he'll initiate dialog with you. You have two options. Side with him and try to extort money out of Reichmann or bring Jullian to justice in which case you fight him. If you kill him you talk to the daughter and return to Reichmann to complete the quest. I've never attempted to help Jullian with his ransom plot but I imagine it's pretty self explanatory.
(added by lothar69)
Update by Woosk:
If you are playing as a priest, you also have a third option to tell him he has to marry Natalia Reichmann under canon and secular law for eloping with her. You will frighten him into running away, leaving Natalia to you without harming her. Returning Natalia to Stefan Reichmann will get you her father's reward(1390 gold), an increase in alignment and 150 xp and both Natalia and Stefan will speak to you to answer your questions. Returning to speak to Sheriff Canterbury however will cancel his quest.
If you fight Jullian by either asking him to return with you, or by provoking him by initially asking for ransom and then saying you want him to surrender to you or to hand over Natalia unharmed, you will get the same rewards listed in the previous paragraph (along with the loot Jullian drops) and you will also be able to complete the quest by Sheriff Canterbury and get your rewards (397 gold and 150 xp).
If you agree to join in on Jullian's ransom demand by asking for half of the ransom money, he will send you to get 2000 gold from Stefan Reichmann and have fun with Natalia while you are away. You will have the option to give 1000 gold to Jullian to return Natalia to you or to kill him to keep all the ransom money to yourself. Returning Natalia to Stefan will get you 150 xp, a decrease in alignment and both Natalia and Stefan will no longer speak to you.

Kill the Orc Chieftan Rashgkar #1 - Given by the Sheriff
The Sheriff in town asks you to bring him the Orc Chieftans head. The Orc Chieftan is located on the bottom level of the Iron Mines. Kill him, loot his head from his corpse and return it to the Sheriff to complete the quest.
(added by maggotheart)

Kill the Orc Chieftan Rashgkar #2 - Given by a Barbarian Spirit
The Barbarian Spirit is located in the Iron Mines. In the second last level of the mines, there is a staircase in the Northeastern section that leads you to a floor filled with hostile barbarian ghosts. The spirit who gives you the quest is in the Northwestern corner of this map, behind a locked door that must be bashed or lockpicked open. The Orc Chieftan is located on the bottom level of the Iron Mines. All that is required to complete the quest is to kill the Orc Chieftan. You don't need to bring his head.
(added by maggotheart)

It's fairly important that you add name of the questgiver into the headline of the quest, to make searching easier.