Templated class and iostream overloading

[beta3designs]

Well first I want to say hello to all the users here.
I'm a beginner in C++ and I'm trying to program a vector class for a Math Utility library I'm working on as my first big project written in C++... Well everything is working as expected but I have some questions.
-Info:
All my vector class is in a header file and using the namespace mut (it stands for Math Utility Toolkit, I might change the name but it's ok for the moment) and I'm using a template like this:

namespace mut{
    template <class T=int> //Default vector storage is int
        class vector{
              .......
        }
}

I wanted to add iostream operators to my class and this is what I did:

//IOSTREAM operators

    template <class T>
    ostream& operator<<(ostream& os, vector<T> &vec){
        int i = 0;
        os << "(";
        for(i = 0; i < vec.length() - 1; i++){
            os << vec[i] << ", ";
        }
        os << vec[i] << ")" << endl;
        return os;
    }

    template <class T>
    istream& operator>>(istream& is, vector<T> &vec){
        int i = 0;
        for(i = 0; i < vec.length(); i++){
            is >> vec[i];
        }
        return is;
    }

So my question is:
I used the template again since these operators are outside the class definition but I don't know if there is a better way or if this is ok...

And a second question is "is there a better way of formatting the output for my vector like so?": (vec[0], vec[1], vec[2]...)
I achieved this format but i don't know if the function can be optimised...
Well thanks in advance!
If you need more info, let me know
BB!