well, you can sell those "regular" clowns to wholesale companies that sell to stores, because they sell them for much more. you can actually make a nice living off of them, getting them at that price.
the 125 is fully stocked in my opinion. all of those fish will get large. i wouldn't add anything else except for maybe something that doesn't move much or require much space, like perhaps a stonefish or angler.
the sailfin is too large for a 135 gallon tank now. you can keep all of the rest of those fish together, providing they are removed when they outgrow the tank.
it's not like fresh water in that you can keep a foot long fish in a 125. i know oscars are ok in a tank like that, but salt fish behave differently.
if you truly care to make the fish a healthy environment, that is.