Thanks for the review. Well, on the manner in which Lyx will store the information, I think making a new class LayoutElements and the Layout Editor could be viewed as an instance of the same, can be one solution to the problem. What goes inside this class is determined largely by the manner in which the parsing of .layout file is done, (which is specified in the TextClass, Layout class ) would be more appropriate as I do not find any other alternative. Since my methods, and parameters in the class LayoutElements depends on the classes TextClass, Layout etc. so the parsing thing which I mentioned as a backend job would no longer be required!
Also, writing/modifying a layout file in whole can be best done by making it into a "local layout" as you suggested, as the feature already exists, so it wont require much work. Therefore I think the project mainly focuses on making the class LayoutElements and making the widget for previewing the things! Would like to hear more suggestions and feedbacks on the above from you!