is the range that one needs to make for a vertex area attack always 1?
You check range from the Origin. For a Vertex Area Attack, you choose the origin as you would for any standard Area Attack. Then you choose two other adjacent hexes touching a vertex of the origin. There's your area. On level ground, the range to the other two hexes is 1, but elevation could change that.
Unless something changed in the final rules. I'll confess I don't have the printed rulebook in front of me.
Ah, elevation. I'd forgotten to factor that in.