You need to test in game. You can use /loadui <uiname> to reload the UI, but this breaks some UI elements (and sometimes crashes the client). You can /quit <charname> to quickly reload your char, which fixes most things but not all. Then there is /refreshuidata which fixes yet some other things but still not all. So it's always good to double check once in a while or when you hit a roadblock by exiting the client completely.
The class name can be taken e.g. from a text element to which you apply the respective data element:
DynamicData="/GameData.Self.Class"
Then you can take that and apply it to an image style. E.g. to quote from my persona window:
OnShow="MainPage.ClassBackdrop.Style="/ProfitUI_Styles.ClassBackdrops." ## (Parent.Parent.Custom.ProfitUI_SubclassDetector.Subclass)"
Regarding the paperdoll I don't know, probably something else is covering it up in your window? It should work fine.