You are correct that we can operate our offense without an RB that can play WR. However, the offense won't do everything they want. They want the ability to line the RB up in the back field then motion him out or just the opposite. If the RB can't really play WR yet, it greatly diminishes what the defense has to account for.
So, we can do it, it's just not optimal.
Yes, but we can still do that. We already have other guys that can do that. So they new guys don't have to be able to do that right off the bat.