About 3 days. At Soviet times nobody cares for plugs because nobody has electronic devices to bring. But there are outlets in restrooms, for electric razors. Guess they can make outlets in trains if sufficient amount of people will demand them. Otherwise good old paper book will carry you through.
Train etiquette are well developed in Russia so there are little issues if any when people travel together (i.e. men supposed to leave kupe in the beginning of the trip to give womens chance to change). Indeed there always could be a bad situation.
Glad you make it to Kazan, it is very interesting city and it give you another glimpse in russian history and present, in terms of interfaith relationships.