Yes, simply go to the IntelliSense Settings page of VisualGDB Project Properties and add “-include <forced include file>” to IntelliSense CFLAGS/CXXFLAGS.
You can change the syntax highlighting colors via Tools->Options->Environment->Fonts and colors->Text Editor. VisualGDB automatically uses the standard C/C++ colors from the normal Visual C++ package (if they are supported in your VS version) and adds a few elements of its own (e.g. “C++ Constructors and Destructors”).