If your banana wrasse is Thalassoma lutescens, then things may not get too much better for the cleaner wrasse, as Thalassoma wrasses are pretty intolerant of other wrasses. If, on the other hand, the banana wrasse is Halichoeres chrysus, then things should begin to get better.
Using a social acclimation box to introduce a new wrasse to an existing wrasse helps diffuse aggression.
First, an hr acclimation is on the long side, as it opens up the fish you are acclimating to exposure to ammonia.
Was there cover, such as pvc fittings for the wrasse to hide in? Being exposed and vulnerable is very stressful to a fish.
For leopards I recommend qt, but more than a few will put them straight into a display. It is possible to treat prazipro in the display tank, it is reefsafe.
As long as there aren't males, leopards can be kept in small groups either same species or different species.
You're going to have a hard time adding a fairy wrasse to a tank with a hogfish. Hogfish are pretty intolerant of other wrasses, so although you haven't witnessed any aggression, in the future you will.
Depending on how bad the stray voltage is, sometimes it is noticeable by putting your hand in the tank, especially if you have a cut or bite your nails. In other cases a volt meter can be used. Fish that are affected by stray current are skittish and in cases of longer exposure may develop HLLE.