Where can I find statistics and costs of aviation incidents and accidents caused by communication failures?

Go to http://www.ntsb.gov/ntsb/query.asp where they have a searchable database of aircraft accident reports since at least the late 1950s.

Got bad news for you. You can get "data" from all kinds sources. You can't get truth. What the "people in charge" of any airline want you to know is flying is safe. Most accidents where the box info is not released, and there are no survivors, are attributed to pilot error. Private companies have no reason to produce the box info. It's always better to blame the dead pilot than to say the plane is bad. You can't fly with the dead pilot anymore, can you? But you can avoid taking a flight on a plane with a bad safety rating. See! Pilot error. Plane is fine.

Try airdisaster.com

it provides information about all accidents in aviation history

http://www.airdisaster.com/ is the source for most accidents, also try the NTSB