Okay, well I am not 100% sure on this, while the bones do thicken I believe it is very little and does not really change your face or the rest of your body much at all. I doubt you can even really tell just by looking at someone.
My face changed completely due to weight gain. When I put on about 40lbs in the first half a year of starting T the added tissue for muscle as well as the fat made me look more masculine. I ended up loosing that weight again and am back to the same size I was before I started T. If I didn't have facial hair I'd have to say that there does not seem to be much of a difference for me personally. My face is a little more narrow than rounded but that's just because the fat distribution is different now.
As for the skull thing, it is natural for everyone's skull to change shape a bit here and there from what I've been told. It has to do with the skull plates never fully fussing and then bones add and loose calcium through out their life, hence they get thicker and thinner more than once in a person's lifetime. This is true of everyone regardless of gender.
As a side note, these are just what I was taught, if you know that some of this is wrong please share. I can't recall if this is stuff I actually read or was taught, or just things I picked up from other people. Damn getting old! Haha.