Re: Waka Sensei question
Waka-Sensei is not a formal title but is generally used to mean young master. It is a reference to someone who will ascend to a position of leadership (as in this case Doshu). When O'Sensei was alive Ni-Dai Doshu was referred to as Waka-Sensei indicating that he would become Doshu when O'Sensei died. The same case existed when Moriteru Ueshiba was called Waka Sensei while his father was still alive. Once, however, he assumed the official title of Hombu Dojo-Cho that was how he was addressed. After the death of his father he then became San-Dai Doshu or simply Doshu.
I hope this helps.