LOL! Good luck finding some of those secret rooms (I think they appear in the Magi module in the temple levels) I have encountered one instance where I 'discovered' the secret room. The passage appears as this small pink 'globe' attached to the wall, you click on it, and it opens up!
To bad about the key issue. One work around I have done, (becuase I am lazy, and I hate going in and out of the town, over and over) is to edit the txt file for the store generation of 'keys'. Each time you go into the town, three keys are always for sale- I upped it to 3 keys of each kind (copper, silver, iron) by adding in extra entries.
I also reviewed the item.txt file (man is that thing HUUUGE!). There is a line that can be adjusted to affect the number appearing in a stack (think arrows and shots, how they appear in multiples). Perhaps all shovels can be edited to appear in stacks of 99 (or whatever number, with a neccessary reduction in weight!) and then the shovels get 'used up'. So say you have ten shovels, what that means, is you can use it ten times before it 'breaks'. Just a thought on a work around...