One thing to keep in mind is that building 3 222s takes a lot longer than producing one vehicle, and the longer the game goes the smaller the window of effectiveness for the 222 becomes. I could see the brits having an issue against a 222 rush, but the usf and soviets have plenty of options to deal with them.
1. Building 222s can also start much earlier. As long as the player doesn't wait, they could build 3 222s before anything but a m20 and AEC.
2. The same could be said about all light vehicles. 222s do have late game versitility as a scout though if they attain vet.
3. Only if they tech correctly. If they go tier 1 or liutenant odds are they likely won't be able to accumulate enough ammo for nades an zooks to counter 2-3 222s whose combined health is now 640-960.