For the key : look in the nearby surroundings of that closed door, but beware of 2 or 3 enemies that appear taking the key ! (if you mean the storeage cave of Naberius you can only go in if you know the password for the Teleporter - see below!)

The Teleporter is nearby the Burned Chapel Scrine, but for that Teleporter you need a password wink

Good luck ! smile

On 7th of february 2015 : I start a new adventure in the Divinity world of Original Sin,
it's a Fantastic Freaking Fabulous Funny ... it's my All Time Favorite One !