Get type in referenced assembly by supplying class name as string?

Maybe the referenced assembly isn't loaded at the time. Also, I understand from your question that you do not have the full type name, only the class name.
You should try something along this line then:

Type type = Assembly.Load("YourAssemblyName").GetTypes().First(t => t.Name == "ShortTypeName");

Hope I understood you correctly.

For the first question, you could do something like

Type t = AppDomain.CurrentDomain.GetAssemblies()
                                .Where(a => a.FullName == "MyFramework")
                                .SelectMany(a => a.GetTypes())
                                .FirstOrDefault(t => t.Name == "Car");

I am not sure what you mean by the second question.