You mentioned the "FW moray eel" and the list of fish that you listed will be great with them. I have similar fish with my eels and there are no issues with the eels. It's actually fun to have them with my scats, datnoids and sharks.
The only worries you'll may face is feeding the eels over the other fish. I have three and one of them prefer to eat pellets with the other fish and so he's no problem. The other two like meaty foods primarily and will starve until I put those types of foods in the tank. The problem is that the scats and the sharks will usually get to the other foods before your eels can (though my eels learned to grab the food right out of their mouths). I found a solution in the form of my vacuum tube. I put their foods in that tube and I drop their food in. They will swim in and snatch their food right out of your hand. Be careful not to let them bite you.
The other thing is their diet. They love shelled fish. So krill and that sort of foods are good. And like snakes they can take down a LARGE goldfish on occasion, but I don't like goldfish for feeders. Their favorite (or my favorite to watch) is when they take down a crayfish. They'll grab and hold the critter and will turn their bodies into a knot and will pull their face and their victim through the hole, breaking the crayfish apart. The rest is a crunch fest of peices. They also do a lovely "death" roll on larger fish.
But again, your fish are safe. They do not bother fish they cannot swallow, and they learn their tank mates quickly. I once had puffers in the tank with them and because they were bite size (I didn't know their maximum size eating fish at that point) they were taste tested and quickly released. After that, they were never bothered again.
They are smart buggars too and I think they will be a nice mix with your fish. I keep my salinity on the high end of the brackish scale at about 1.016 - 1.020. I think all of your fish will appreciate that salinity.
Oh and while I have had some serious diseases infiltrate my tank, my eels never seemed to be affected.
Bah, I can go on and on, but your fish are safe. Enjoy them.
