TRAC is not applied during limp mode, the ecu just prevents the car from running normally, the TRAC light indicates that there is a fault
id say you have done more damage driving the car around in limp mode, than the original issue which caused the limp home mode.
id suggest as Stav mentioned that the metalic noise was the tensioner failing and the belt may have jumped a tooth, its also likely that the cat has now failed due to over heating due to running in limp mode for a long period.
limp home mode is just that....limp home