Regarding imagination: you said "imagine a portal and jump through it, and talk with whatever you see there" this is what I do, but its not as if I'm "there" at all. I'm quite distinctly "here" sitting on a bench in the park meditating, while I imagine jumping through a portal or speaking to a wizard (I like to model things with magical symbols lately, its been productive). But I am here in physical reality, while "imagining being there, doing this, doing that" not actually DOING it. Does that make sense? Can you speak to that?
From my own experience, my overanalytical, thinking, judging mind is far too dominant for me to just sit down and immediately start imagining I am in the non-physical--if I do that, I'll just sit there going from thought to thought, getting distracted, unfocused, and bored. For me, I must first quiet the analytical mind by getting into a meditative state, either through listening to a guided meditation, binaural beats, or doing my own meditative process. I do actually employ my imagination to get into a meditative state: I first breathe very consciously and evenly, breathe out all my distracted and negative energy, and breath in calming and colorful and empowering light energy through my crown chakra, down my spine, down my pelvis and legs and feet, back up through my belly button, solar plexus, heart, throat, into my head, surrounding my body, and do this for several minutes or longer (sometimes this is all I do, which is OK). Then I imagine a very high spiral staircase sprouting up from where I am sitting, which I begin to climb very slowly, feeling the steps and the cold railing, periodically looking down at my body, my home, my neighbors' homes, then my city, the city 25 miles away from me, then sometimes as high as the earth itself, then finally get to a wide platform that has a comfortable reclining stone seat that fits my body perfectly, and I sit there and again, try and transcend the subtle non-physical body, until I am floating in the sky or in space, until I am no longer processing my physical body and senses.
It has taken me nearly 20 years to develop that process, and I'm not successful every time I sit down (often I am not able to get there at all), but I am finally able to get there some of the time, and from that point I can use my imagination in the non-physical. Imagining healing myself or my loved ones or other people (I love Jack Angelo's Distant Healing guide
, imagine I am communicating with the LCS/my guide and ask questions and get information, imagine communicating with other people, imagine jumping through the portal and having no idea what you'll see there (giving the LCS an open invitation to send you a message). Sometimes it is just imagination, other times it is definitely and obviously real, sometimes I have no idea. At this point, I would still consider myself a beginner, so I'm just trying to have the experiences and understand. As I said earlier, save the judging for later on.