I've just killed the zombie guy in the crypt called Flokis Ra, but I haven't got the gold key behind the bars, and I don't know what to do with the statue. And the guy that Kerielle (the girl at the windmill) wants to talk to is a puzzle as well. Thanks!

The gold key you can get only much later. F'Lokis Ra should heve left an amulet: read it (right-click and select read) and tell the statue what it says.
Kerielle just wants the amulet of that guy Algamesh. You'll find it soon.
(You can also check the walkrthrough of the crypt that the game provided: see the online help.)

You can find Algamesh's Amulet in a chest through the second door you run across, from the entrance of the Crypt. The door is locked, but doesn't require a key. Just pick it or break it, and you can get in.

Heres a little tip, if you want to gain some extra exp points, rumphy keep returning after you kill him. Kill him then go back to the statue and then go kill him again and again until you get your guys strong.
I did this with the whole party and then did it with three guys and then with two and it helped bring up exp ponits for all.

have fun.

Thanks for the tips!