Increasing/decreasing, minima/maxima

Okay, so I'm trying to find whether the graph is increasing/decreasing, and I need the minima/maxima.

My original function was x^3 - 4x

First derivative: 3x^2 - 4

I've gotten down to sqrt(4/3). Now, from here I am confused on exactly how to get what I mentioned above (increasing, etc.) I can do it with other types of functions but I don't exactly know what to do in a situation like this. Any help, please?

And as a side question, can someone calculate the concavity and inflection points and see if they get (0,0) for inflection and (1,inf) for concave up and (-inf, 1) for concave down? I want to check if I am at least doing that right.