Languages: Drow/elven is very close to elven. Its basically elven with lots of extra words for different types of treachery, hatred, and murder, and very few words describing concepts like nice, love, and peace.
Undercommon is very different from common. Most drow speak a mix of elven/drow and undercommon.
Drow also have a silent language of hand signals, because noise carries far in the underdark.
The first couple of posts in the OOC thread talk about the family house structure, but basically, the Matron is in charge and is an absolute dictator. Everyone derives whatever authority they have from her. Her two daughters have somewhat more authority than everyone else because one of the two daughters is likely to be the Matron's heir someday (i.e. they are potential future absolute dictators). The rest of the characters are other nobles in the house, either children, relatives, or the house patron. Their authority and power depends on the Matron's favor.
Most of the house commoners and other nobles are presumed dead (slain in the revolt) except perhaps for some of the members of House Millithor that are working for the merchant guild (company of the coiled whip).