But a unit design is restricted to a race, right? I seldom play empires...

No the AI doesn't upgrade outposts.

No I haven't seen an AI unit on a warg, and I know there are default units that should ride them like the Wraith "Tide of Teeth." Wondering if the AI "upgrades" them to horses or something. I've never really thought about (or noticed) this one until now.

I've also never seen an AI using one of my unit designs. I've made a lot of them, from early game to late game, I have never seen one in the hands of the AI, not since beta anyway.

The AI not grading outposts, and a rather exploitable outpost system, is why I really would like to see outpost reform if not in 1.3 or beyond, it is something that definitely needs to happen in the expansion.

Spam consulates to get your cities up quick. Also works well together with sacrifice for mana after they are lvl 5.

When I do simcity, I always end up with 6+ consulates pr city to get their growth up. (most of my cities are conclaves not towns )

I can confirm, with screenshots if you need them, that the AI is using my design. You must have played the faction before though, for example Pariden is using right now a design called 'Rank Archer' which is definitively from me.

As for upgraded outposts, side question, what happens with several outpost providing the same bonus in the area? Say 2 stables, do I move at 3x speed, or 3 abbey, do I produce mana when I cast spells (or they cost 0, which is barely less buggier). I hope bonuses are not cumulative in fact.

Same here. 

Now that I was looking for it I also saw some warg riders, the very ones I mentioned before, a stack of Tide of Teeth from Resoln.

Still haven't seen an AI sov or champ on anything but a horse though.