I'd like to hear some discussion on this too. This has been the second summer with our pond. Even though it's big enough for koi (about 700 gals.), I'm afraid to try them. I put feeder gold fish in and within three days about half are dead. If I've kept my numbers right, I should have 17 fish in there. But, really, there might not be ANY gold fish in there. All summer the pond looked like pea soup. Now the algae is under control, but the fish are expert hiders. I also have 6 four inch placostomus.
As far as plants, I simply don't have a handle on that one at all. When I purchase a plant, I might as well buy the funeral plan to go along with it. Right now I'm making do with plastic water lillies. Silly, but it works.

and so far I haven't lost any. I do have lots of damsel/dragon flies. Pretty neat.
Sorry I can't give any advice. I'm still in the boat of needing advice myself.