1) a map can be found here
http://www.planetbaldursgate.com/ima...bg-citymap.jpg
2) Kill an Ankheg, take it's skull with you and bring it to the smith thunderhammer in Beregost. He will respond automaticly when you talk to him and offer you 500 gp for the skull. Decline this first offer, and he will offer you to make an Ankheg armor out of it (it will take him 10 days to do so and it costed me 4000 gp (my reputation was 20).