Welcome to the forum
Just posted this earlier today on a another newbies thread:
Noisey thrust release bearing - very, very common issue and normally nothing to worry about - see here:
viewtopic.php?f=9&t=16709&hilit=thrust+bearing
As regards the metallic noise - might be best to get someone to listen from the passenger seat and see if it is coming from the front or rear of the car.
It could be a number of things, but for starters I would check between the disc and the backing plate to see if a stone or something is lodged there. And while checking that area make sure the pads and shims are OK - the inner pads are known to wear more.
It might be a wheel bearing although you don't normally hear the symptons associated with wheel bearing noise as 'metallic'.