I am in the same boat as you. I have a player who has created an alchemist. As far as costs, DCs, etc; I am just making it up as I go along. This means that the player has to understand that I retain the right to change things as I go along.
Remember, this is a game. It is our job as game...
Unless the PCs have a wand of Knock, it doesn't seem to be a big problem. Every spell slot used for a Knock spell is one that can't be used for something else. These things tend to work temselves out.
I have several questions.
What do the drow think about all this? Will there be more raids?
How well do the Elves and Dwarves get along? Is there a clash of cultures?
Who do the Dwarves trade with? What do they trade and what do they want? Do the Dwarves have expansionist policies?
What...