Getting frustrated !!!!

1) I have placed both red gems in the imp statue. Nothing happens. What is supposed to happen? Maybe the door open to get at the gem?

2) I have a mirror that says it can use a key. WTF is this? Does not seem to work on anything.

3) CANNOT open door at location #11 on map that leads to level 2 pipes section. This is bad cause it leads to an area on level 2 that is the only area I have not opened up. (almost all of the eastern section of lvl 2) This door is right next to the imps that are beside all the potions on a table.

ANY help would be appreciated.