No such thing as too many! In a tank that size I would go with at least a dozen or more. They are much more fun when you get a confident group going. Otherwise they hide all the time.
Much agreed, 5 minimum but more would be much better. You will see them out much much more.
My loaches eat daily in the morning, I feed one day cichlid pellets (floating or sinking), one day algae disks, and one day blood worms. With the frozen blood worms I drop a frozen chunk in and they come running. Most times the oscars grab the frozen piece shake it all over the tank and the loaches just follow the worm trail behind him.