depends on size, ornates get fairly large. The plecos will be fine. The festae would be fine unless it is a very large ornate, but I have seen some very aggressive ornates. Mine chases anything that moves in front of him, but all the other fish are too large to eat. I dont know festae growth rates, but Im assuming if you start with a smaller ornate that the festae will remain a good size bigger that the ornate will never pose any real threat.
They will eat pretty much any food offered on the bottom. Beautiful little guys, IMO they are some of the prettiest polys. Take second opinions but I dont think youll have any problems with that mix