The gender stat is just there since it is only possible to play as a male.
You see that shit? I’m making moves. 
Getting Ulfberth grants you a small boost in valour if I’m not mistaken. If you have a bastard son with Marguerite you can bring up the issue for your bastardborn son and later (after the hastilude) duel the Viscount for the title. The only time when you can get a position in the Privy Council is right after winning the Succession War.
What do you mean?
Talk to her after the war with Valmagne, the one where you get to capture/duel/kill King Louis. You’ll need relatively high nobility and courtesy, with 60% in both stats you should be able to get her to talk to you. Let me know if you were able to get her to talk to you. Also, there is only a 50% chance that Marguerite gets pregnant from this encounter. Have that in mind.
No, there is only one opportunity to learn Valmagne. Sadly, those girls are only there for “world building”. I had the same question when that chapter was being developed.
There is still more to experience. 
And, yes, the possible sequel will feature the twin sons of the 5th Earl of Aswicdale. At least that’s the plan.
I think that most, if not all, the possible brides are a couple of years younger than the main character. Hopefully @Goshman can give you a more satisfying answer. (Goshman, sorry for throwing you under the bus like this. 
)
Finally, someone managed to access that. Well done, Sir and/or Madam! 
What are your thoughts on that path? Which one did you like more?