Apart from the brits leaving the frenchies to the wolves i havnt seen anything to out of the ordinary. i broke the axis with Rome as they invaded albania (no point getting involved with a drowning man :-D )
Kill Japan. If you do it right, Japan has no chance to survive. America does become a beast, but that’s okay because England and Russia out number Germany, thus they can defend nicely and wait it out.
And, yes, it is legal for partners to talk to one another. There is no limit to the number of times, so you probably need to set a number of times or a time limit, if it bothers you.
We never play with victory cities. If Moscow or Berlin are captured, we can see the way it goes, and then the part who has lost a capital city give up.