As the title says. I did it by manually adding the vertices, then subsurfing. The wireframe in the second picture is that of already subsurfed mesh; however, as easy as modelling basic shape of the face is, I still have problems with creating the entire head.
Very good, at least it’s not one of those neutral-expression-make-human face. I like it. By the way, you did use the mirror modifier while modeling, right? Mirroring can save you tons of time.
I didn’t know of mirror modifier at the time, I’ve used duplicate/mirror axis/merge vertices method.
that works too, but it’s hard to visualize the look when one only have half-a-face. 
Very good, at least it's not one of those neutral-expression
There’s a good reason to make neutral-expression faces if you plan to animate later. If this face is intended to be animated, you should have the expression be as blank as possible, and create the expressions in a way that they can be animated, either with armatures, or shape keys, or lattices, or some combination of those.