We can assume some astral projection or OBE so yes it would be possible. Theoretically you can reach your previous lives, other people's minds, some kind of shared human (collective) consciousness or maybe boost your brain to be able to learn something just from memories, when you for example saw someone playing an musical instrument. Those are just theories, yea possible ones but I never saw anyone who would be able to do so.

Who knows. In my opinion, it's possible maybe, but it would take a lot of time or maybe even using some special, not very well knows techniques to achieve such things.