One of the drain plugs screws into the sump plate, can't miss it. If you pull the sump plate be careful with those little bolts.
Three quarts will cover refilling, pour in two and then check the oil level on the dipstick to bring the level up to between the two lines on the dipstick, you wont use the full three quarts. Rest the threaded plastic section of the dipstick on the engine case to get your between the lines measure.
If you think there was a chunk of metal in there then by all means try to find it. There are magnets on both drain plugs that can catch debris, there's also a small magnet on the sump filter that can catch debris, like little cam chain master link side plates.....lol. Sometimes just draining the oil will expel a foreign object. Your call on how far you want to ease yer worries. Good luck!