For R# action annotations details please check the following link - http://blogs.jetbrains.com/dotnet/2011/12/providing-intellisense-navigation-and-more-for-custom-helpers-in-aspnet-mvc/

And regarding additional actions for url builders - usually I have the action which provides the data for the grids in the same controller so I would prefer to write "... .Read(read => read.Action("LoadSitesData", new { id = Model.StudyId })" instead of "... .Read(read => read.Action("LoadSitesData", "StudySitesAdministration", new { id = Model.StudyId })"