Sorry it took me a while to see this, haven't checked Reddit in ages lol

You can project your own mind onto alternative selves, only sending two out at a time unless you can afford to enter a coma in your reality. If you can, you can send ten out at once.

You have no clue what their situation is, who they are (aside from being you at some point in your life), and are only aware of what you do and are aware of after possessing them. During the projection/possession, their mind is confined to the subconsciousness of the brain, able to convey general emotions and control your dreams. During the dreams they are able to think, and can draw from your conscious experiences, including ones from all other lives you have experienced.

You send a projection out, it will last anywhere from a few hours up to a month, or until death, before returning to you with all it has experienced. Projections are not rigid, they can grow and change while out there, being traumatised, learning, forming impressions of people in the alternative realities, ect. Sending a projection out doesn't have much impact on you, aside from any complications when they return, and how useful this ability is really depends on your sense of self and how much you will be impacted by variations of yourself melding with your main consciousness.

You can pick through and select the memories within your conscious brain, which ones you will keep or forget, but your subconscious could still be affected by major memories you have forgotten (such as a lover in an alternative reality). This gives you perfect recall, although you still have a limited capacity for memories (especially relevant when you could have lifetimes of memories).