1. Sad, truly, you can only fight for over four years, not that you have enough natianol morale to fight over that many rounds anyway.
2. This is valid in the base concept, it is stupid that it gives you massive benefit for suicide attacks, but you also should not allow those suicide attackers to enter you territories, so this is pretty much a once you can be defeated that way, than you will avoid it.
3. This is just plain stupid, massive difference between starting technologies, and those give all nationalities the starting base difference, after that, it is your choice to be just as stupid and bad as the historical leaders were or do better with hindsight and common sense.
4. Yes, the Baltic is a one way sea lane, mostly becouse it was a one way sea lane IRL, several British units (mostly subs) forced to be interned after the Russian collapse, since they cannot leave and had no friendly ports. Denmark get anoyyed for each unit (not much, but it can add up), but i would probably not DOW as Denmark on England, for sending lots of ships, with more marines on them, than my entire army...