That's an over-simplification but yeah, that's about it.

I also forgot to mention that children get the last skill that the parent learnt carry across. So if possible, try to get the girls to Dark Pegasus so they can learn Galestorm, for example. Oh, and no children can become a Dancer.

I certainly hope that list is non-definitive, because i chose female avatar...

they get father or mother skill?  or both?

Mother skill. The Father's pretty much useless, sadly.

It is non-definitive. The only difference is you'll need one additional pairing for it to work and Morgan will be Male as opposed to Female, so will have access to different classes. However, each female character can marry a handful of male characters, so it's just who you fancy pairing together to get the greatest stat boosts.

I finally beat Chapter 11 without any deaths. It wasn't easy considering in the end, what I needed to do was make sure none of the extra enemies could spawn in the forts (except for the ones surrounded by mages).
It was very satisfying once it was done, though. Sometimes pairing up isn't always ideal.

A useful tactic to know, really. Forts also give you extra defence and some HP back so it's often good to put your weaker characters on them, as it also blocks enemies appearing as you said.

I hear the difficulty really ramps up around the point you're at, so only expect it to become even harder from here!

Hmm good to know.  Almost wasted a lot of time.  Was going to get Rickon to be a Bow Knight so I could get the skill Bowbreaker, and then pass it on to someone who rides a pegasus or something that is weak to bows.  But guess that would be a waste of time now wouldn't it.

I hear the childs hair color is determined by the father's hair color.  So his seed does do something.

I did not know that, I guess that's why Lucina's hair is the only one which is the same in all artwork? 

They also get the father's hair color and he does help with thier stats.