The 30 seconds was a typo, I fixed it. It is actually 15 at the moment.
And think of it as more of a transformation/transition than just being helpless. Something like the way templars formed archons in Starcraft, for example.
As to the upgrades - if you knew the looks of the units a bit better the differences would be immensely obvious. Once you play a little bit it is easy to see the difference between the orc upgrades