I attempted to break loose the headset last night, but it didn't want to move. I unscrewed the allen bolt in the stem several turns, and gave it a few taps--I didn't see it move. I'm a bit reluctant to wail on it just yet, as I'm afraid of what I might break; and it is currently a ridable bike, albeit not as comfortable as I want currently (or think I want). I did measure it, and there is about a 3cm difference in height from the top of the handlebar to the top of the seat.

I did move the seat forward, but wound up with the nose about flat--if I tilt it up as in that last photo, it just doesn't feel quite right. I suspect I could raise the nose up if the bars were up more, but where the handlebars are fixed for now, I think the angle is about right, and I need to figure out how to support my upper body better. I may need a seat that can slide forward more.

I think I'll try some more rides, and see if I still find it uncomfortable or if I start to like the position better. I honestly haven't ridden that much.