Personally I think Agriculture + Wheel is better (the reason being that you will eventually need both wheel and mining, so why not start with the more expensive one and tech the cheaper one?).
I agree that a fast settler doesn't sound so great. It will get consumed in a few turns anyways.
As for UB...maybe a forge that gives, say, +1 to all tiles with 3 (kind of like the Financial trait)? Would certainly help with Industrious wonder-building. (Or along, the same lines, a library that gives commerce...or a granary that gives food...)
As for UU - a little while ago I had an idea of making a custom unit that had an innate ability to ignore enemy terrain defenses. That is, enemy would not receive defensive bonuses from hill, forest, river, or city walls/culture defense. But the enemy would still have fortify bonus, promotions, and unit abilities. Maybe a little overpowered, but you could compensate for that by decreasing the strength of the unit.
The Wheel is a useless tech to have initially for wonderspam in most cases. It's really only useful in the early stages if you have Marble or Stone in the BFC and not a river, and if you have Marble or Stone in the BFC, it's usually better to settle on it. The 1 or 2 turns you save doesn't really make up for the fact that you have to research an extra tech to get to Bronze Working or Polytheism.