Ferrying or Bridging ?

[Engelbrekt]

I see. But in a 7 turns scenarios, you don't have time to build a bridge, do you ?

Depends on the Bridge value which can be found in the PDT (press F4) but 7 turns is a bit short maybe, especially for the Russian with their low morale engineers. But it could work if you are lucky.

And can you ferry HQ ?

No, only Foot units can be ferried by engineers. HQ:s are most often motorized.