I can reproduce all of those.
For (1), I propose that the Skin Name field should be non-editable, and have a separate button (usually the "pencil" icon) to show a popup entry dialog for editing the name. I doubt renaming skins is all that common, and it certainly doesn't need to happen on every keypress. But if people object to additional popups, the field could be editable but only commit the changes on ENTER or if a "tick" button was clicked.
For (3), single-click to edit in a list is rather non-standard (double-click might be more expected). I propose to have two named entry fields below the list for "From" and "To", rather like the key/value fields in the Entity Inspector, with the fields reflecting the currently-selected list item and allowing changes (committed on ENTER or button click).
Not specific to the skin editor, but I think we need an application preference for monospace font size. Reading the declarations is really difficult on my 1440p monitor.