RE: metal in oil
Hopefully, the metal is from a slightly loose muffler. Put in a new glow plug and make another flight. Then carefully inspect the plug and element to see if an metal has attached.
The nose dropping in the turns is usually due to the higher angle of attack of the downward blade in the turns, since the airplane is pitched up at least 4 degrees relative to the path of the airplane in the turns. Since the blade on the right side is doing most of the pulling, you end up with the nose down tendency. Most have to put a small amount of weight on the right wingtip to compensate. Some are experimenting with electronic mixing schemes to compensate. Lead tape from a golf shop works for me.
Other possible problems that can result in this is being slightly nose heavy, or having left trim in the rudder or even left thrust (though that causes problems on takeoff).