The fourth idea is terrible. More iron = makes iron things faster roffle. That's Starcraft-level simplification.
While it's true that complexity turns away players, let's all be honest for a moment - people who don't want a certain level of complexity will not EVER buy this game. Remember in the early 21st century when RTS games turned their back on ever-growing resource lists to go back to the standard 2 or 3? The people who drove that aren't going to buy a fantasy-themed strategy game with management, no matter how much auto-fighting, governor AI or simplification you put in and chasing that market will only hurt the game by placing it in a middle, nowhere place.
If economic complexity can be added back in with mods, who cares (I'll just never ever play vanilla, like Stardock's other games) but sacrificing the opportunity to make something interesting for 'lol iron = +10% build speed' isn't going to broaden the audience to the degree some might expect. That said, as much as I'd like the original approach, without a great UI it'd be horrible crap, so the third idea is probably best (ie, economy with resource movement rather than massive oversimplifications but not requiring ludicrous juggling).
EDIT - Ok... so the link for the resourcing system lead to the map designer thread. Hooray? 