No, IIS Express is meant to be an Express version, thus the name, and there are no GUI plugins available for the applicationHost.config
However, if you are not sure of what the different sections in the applicationHost.config actually controls, have a look at the Config Reference at http://www.iis.net/ConfigReference
Another approach, although somewhat exhausting, would be to make the configuration changes to your "regular" IIS installation with the Remote Administration tool, check out the differences it produces in the applicationHost.config, and apply those to your IIS Express configuration.
PS. do yourself a favor and use a text editor with XML syntax highlighting, it makes it a lot easier to spot any typos with regards to correct syntax.