And as for the key shops, you can do two things:
1. You can add the keys in merchant.cs to one of the shop regions then add the merchant object in the map and then put the shop region over them. These are randomized tough, so you might get duplicate item, the better option for keys would be number 2
2. Use the edit button on the merchant object's tile in the map editor, and then add in your price, objectid and currency. This is what you would need to fill in:
mtype:0xfbd;mcost:200;mcur:1
the mtype is the objecttype, the mcost is the price and the mcur is the currency (1 = fame, 0 = gold)
If you want me to go into a bit more detail, you can add me on skype