Problem 1

struct __declspec(dllexport) MyStruct
{
   int a, b;
};


extern template class __declspec(dllexport) std::vector<MyStruct>;


class __declspec(dllexport) MyClass
{
private:
  std::vector<MyStruct> m_vec;

public:
  // more code here
}

c:\Program Files\Microsoft Visual Studio .NET\Vc7\include\vector(35) : warning C4251: 'std::_Vector_val<_Ty,_Alloc>::_Alval' : class 'std::allocator<_Ty>' needs to have dll-interface to be used by clients of class 'std::_Vector_val<_Ty,_Alloc>'
        with
        [
            _Ty=MyStruct,
            _Alloc=std::allocator<MyStruct>
        ]
        and
        [
            _Ty=MyStruct
        ]
        and
        [
            _Ty=MyStruct,
            _Alloc=std::allocator<MyStruct>
        ]
        C:\CPP\Test.h(9) : see reference to class template instantiation 'std::vector<_Ty,_Ax>' being compiled
        with
        [
            _Ty=MyStruct,
            _Ax=std::allocator<MyStruct>
        ]

Problem 2

template <class T> __declspec(dllexport) void MyFunction(T tData);