RadStyleSheetManager works only for embedded CSS files. Your custom skin is not located in an embedded CSS file, so please remove the two StyleSheetReference from the RadStyleSheetManager tag.
With regard to the RadEditor icons - is this with a custom skin or with an embedded skin? Please check whether the background image for the Editor tools is loaded correctly. The background image is normally applied to <span> elements placed inside <a> elements.
Generally, when having problems with styles, you should check whether all required CSS files are registered on the page and whether the problematic styles are not overridden by other styles.
If you need assistance with any of the above, please provide a simple standalone runnable demo or a live URL.
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