fashtas: I've just started and been playing the "intro" a bit to try and get used to the combat, exploring everything (Considering several skills can be gated from you if you miss them the first time)

Down the well, in the servers (The Secret Entrance) there are several locked gates. One, immediately to the right of the room you encounter your first monster, is in a room where your Wolfs Head medallion glows. If you use the medallion, the locked gate glows RED

According to GameSpots "walkthrough" about the sewer (I call a walkthrough VERY loosely) :
"If you run into a locked door, the key can be found on one of the bodies in the next room"

1. There is only 1 body in the previous room, the one the monster was feasting on when you arrived. No key there (Money and a sword I think)
2. There are other locked doors, closer to the exit, but they don't glow red
3. There are no other corpses I can find, with the exception of the monsters once you kill them
4. There is nothing else "usable" in the entire place except the torches in the penultimate room (and some coins on a table plus loot off the monsters)
5. The "glowing red door" room fires off the tutorial about places of power and using the medallion. It mentions "red glows" (or similar) which you enter to increase your characters abilities . I can see nothing like this except the glowing red gate. I *DID* however once get a temporary vitality or healing buff of some sort. Not sure how, it was after using the medallion near that door. the buff lasted about 5 minutes then faded. No idea what it was, just a red cross on the GUI
6. There is a weak wall you can break nearby, it has a sword behind it

Is this just a wild goose chase? Is there anything here?

mundell: You can get into the sewer by walking past the dude that sells steroids and his big brute of a buddy on your right and going to the door across from the tower. It is unlocked with stairs going down to the sewer.

So if you face the steroid dude and his buddy it's the door on your left.