For many string operations such as appending, inserting, overwriting etc. the memory management can be made automatic as well in C, and I think this is the main advantage. Just automatic free at scope end does not work (without extensions).
You can make strings (or bignums or matrices) more convenient than the C default but you can never make them as convenient as ints, while in C++ you can.
Yes, but I do not think this is a good thing. A programming language has to fulfill many requirements, and convenience for the programmer is not the most important.
