First off, when in doubt (with an established or QT tank) do a water change. Second, those fish are going to quickly outgrow that system. The maroons will likely take it over, and personally, I think that would be a nice display. I'm assuming you started with a small trio, yes? You may want to act preemptively and remove the damsels now. That would do two things--reduce bioload very quickly and allow the maroons better room to do their own thing.
Ape, I believe that model Whisper is a H.O.T. box filter (someone like John Henry would probably know immediately, I no longer dream in sku's). For a small fish load what I'm picturing would likely be sufficient. But for active, aggressive fish that are going to grow quickly (all of these fish can likely get to small pan size, or about as big as a man's palm) I don't think it's sufficient. Not without a skimmer or some other additional filtration in absence of frequent water changes.
The number of pieces of live rock doesn't tell us much. Those four 'small/med' pieces could be the size of an orange or a watermelon. Type or source (Fiji, for instance? Tonga?) and pounds are more helpful information.
What else...? I don't know, but I'm getting tired of my fish library being packed away in a place I can't seem to locate. :? I like reading my fish books, especially the bibles.
Oh yeah, you can upload pix as an attachment (see bottom, can't be too big or it won't upload) or as a link, but for some reason Photobucket is giving me grief (ask Len).