Good topic, great questions.
I’m going to suggest something that might sound a little bit counter-intuitive, but this is my experience.
How one knows is very personal. Without wanting to invoke a cliche, when you know, you know. It’s like — how does one know when they type on here, that their words go anywhere? You know because you get feedback. You communicate. You receive a response.
That answers some of your other questions as well— can you feel him? Yes. Do you communicate? Yes. Do you receive divine experiences? Yes.
As for the rest— how do you know? How do you know it’s not your imagination, or you talking to yourself? This is the counter-intuitive part.
Conflict.
As
@Magenta revealed from scripture— the Spirit testifies with our spirit…. For there are two living in one house.
@PaulThomson pointed to it beautifully. We are the house— the Spirit we are given co-habitats us. Living in is and through us, with our own spirit. The question is- “ Who is the master of the house?” Who is lord? Is the Christ in us a guest, a visitor, a companion, a friend, counselor, trusted advisor?—- or is that Spirit actually Lord? Have we made him Lord? Do we trust and obey, or simply hear him out now and then when we get in a pinch.
See, I know the spirit in me. It can be selfish and spiteful and deceitful, full of lust and greed and malice towards enemies. But Christ calls me to set my spiritual nature aside with respect to all of these things and to follow him. To make my spirit secondary and to use my free will to set aside my “feelings” and work to emulate those things that I’m prompted by him to do instead. Love my enemies, seek the good, do unto others as I would rather they do unto me. Forgive, serve… and so on.
It is this conflict within in me— this constant battle that reveals the presence of one that is not me. One that is truly good, pure and holy all the time, not some of the time— when my spirit yields.