As far as the goldfish go, I'll let other handle that but be sure you have room and everyone will be happy.
As far as feeding the clown is mostly herbivourous, so algea wafers, blanched ( or otherwise softened) veggies such as zucchini, cucumbers, romain lettuce, canned green beans, ect. Almost all pleco's like some driftwood to cling on and rasp as well.