What your doing will work. If you have no other fish in the tank their is no reason to use the containers. Just dump the eggs in with the java moss. If you want to keep a close eye on them keep them in the containers. Just change out the water frequently.
Once mine hatch i just keep them in a breeder box in the tank their going in. That way once they reach size i can just release them.
To feed i hatch brine shrimp. I do rinse them with tank water before i feed. I also put a drop of liquid baby vitamins in the bbs before i feed. I also use Golden pearls at 100 microns.
I thought I shouldn't go water changes on the fry trays?