I'm with you on the stat changes. I figure it should weigh 1250 lbs. Basically, I divided the iron golem's weight by its height, and multiplied the result by 3 to arrive at this number. It's a much cleaner number than dividing 5000 by 3.
I can't figure out a formula for the DCs on Craft checks, so I'm just copying off the flesh golem (DC 13).
CONSTRUCTION
An iron man’s body is sculpted from 1,250 pounds of pure iron, smelted with rare tinctures and admixtures costing at least 2,500 gp. Assembling the body requires a DC 13 Craft (armorsmithing) check or a DC 13 Craft (weaponsmithing) check.
As for the rest of the construction, I still can't figure out how they came up with the XP costs. They don't match the 1/25 of the gp cost rule of the Craft Construct feat, unless I'm missing something. (For the iron golem, 300 XP can be attributed to limited wish, but the other spells have no XP costs).