A pull on drum brakes is usually a maladjustment; but together with the scraping and release issue, I'll guess that one set of shoes is rubbing on the outboard SIDE of the drum. Looking inside the drum, it should be obvious.
Perhaps a rear drum has been inadvertently installed on the front.
Or like Pishta is alluding to, the park-brake return spring is rubbing on the drum as it turns.
Don't forget that the self-adjusters have left AND right hand threads and therefore are side-specific. If one is wrong, it will un-adjust that side, soon causing a pull as the other side is doing all the work.