They wear costumes resembling praying mantis. They are extremely dangerous and only kill when they are contracted to do so.
They were spotted in the palace right before the kings death
Dimitri hired Gaedrum to do some kind of service?
Attacked Taralynn Vendnar but she survived- Taralynn saw them, there is not actual indication that they pursued her or attacked her.
They took molly to Gaedrun - This has not been confirmed. All you know is that She saw them at Daedren's.
They broke Taralynn out of jail?
See the contract on Ciodoru for more information on their history.