Short version, yep, will need a full rebuild.
Copper fillings in the oil very highly likley means the crank bearings are damaged (could have ring land issues, but untill its stripped you wont know. although ring land failure is common so would be no surprise)
As far as what you do its up to you really, a proper reabuild wont be cheap if done properly, If the shell is solid and you plan on keeping the car long term may be worth the cost. Rolling shell of a wrx isnt worth much, maybe 1-2k at best, it's doubtful the cost of a rebuild will increase the value of the car to make it cost effective to rebuild then sell.