Re: Spill over
I think mostly not. I've practiced with students of teachers with high-level skills who seemed to have picked up very little from osmosis. Conversely, teachers I know who are successful in passing on skills generally have very explicit ways of describing what they're doing.
Daito-ryu as O-Sensei taught it through the 30's seems to have had explict practices to instill IP skills, solo exercises particularly. After the war, those same exercises seemed to have been treated like warm-ups, optional for aikido practice.
So I'd argue mostly no. If you want to learn them, they have to be taught.