Class 7: Halacha LaMaaseh and Minhagim of Kiddush

[Marsha1]

Now I think I understand more of the concept of arvut and what does or does not apply to women ie. if a woman never has a d'oraita obligation for a particular mitzvah, she can't fulfill a d'oraita obligation for someone else because of arvut; yet, if her obligation is on the same level as the other person's, either d'Rabbanan or d'Oraita, she can fulfill someone else's obligation by saying it for them (because she is also responsible for others' obligation if it is on the same level).  So now, I'm still waiting for the class on challah to find out what is a man's and woman's obligation in saying HaMotzi--but it would seem to make more sense to me now that a woman could say HaMotzi for all others present if the obligation is on the same level for everyone. 

Regarding kiddush and bircat hamazon: Is a woman's obligation for bircat hamazon always d'Rabbanan?  The class seemed to imply this, if Yannai's wife could not say it for him.  What about kiddush?  Is the obligation for both men and women d'Oraita?  If so, if a woman davens maariv either in Shul or at home, even if she is not obligated to daven maariv, or says Good Shabbos, (or lights candles) would this possibly satisfy her d'Oraita obligation of kiddush, so that she and her husband's obligation would be on the same d'Rabbanan level (if we follow those who say that saying the words is fulfilling the d'Oraita obligation) or, if those don't apply, that they are both on the same d'Oraita level at the Shabbat table as kiddush is about to be recited--then, could the woman say it and fulfill the obligation of everyone present, including men?  It would seem that, if I have applied the logic above correctly, that it should be okay.

I liked the discussion of whether to sit or stand for kiddush; I've seen many people do it different ways and never really understood where this came from.  Not having any family tradition for either of us, my husband just chose to sit because he preferred it; now I can give him a valid reason why this is okay!  I also like the idea of washing before kiddush and following kiddush immediately with HaMotzi--can we adopt a new minhag like this, since it was originally Ashkenaz anyway??  I find that there is often a big gap, especially if there are guests, between kiddush and HaMotzi and my guess is that this would be eliminated if we washed first.  We were once guests in a home where this was the minhag and I liked it back then.  It may also be easier for the kids to wash and remain quiet if one bracha (and its action) is immediately followed by the next.