I’m sure I don’t deserve it but thank you! haha 
My personal model is that it’s a bit of both. I’m convinced that I’m a sovereign spirit, first of all.
To explain my answer I have to outline the rest of my personal model, because it may be different than yours - there’s many other ways of modeling how souls work, and for some of them my way will not make sense, it’s just what I operate with for now …
So I use the model that as that spirit, which is a kind of personality-free shard of the tao, I’m incarnate into multiple bodies of increasing density for the purposes of experience reality at different levels and energies. every layer brings my raw, function-free spirit new info, abilities, experience and purpose. I didn’t get emotions until I “put on” my emotional body. I couldn’t experience the astral without a mental body, I could not experience the physical without a physical body, and the qi body is how I sense and interact with qi/energy. etc. The bodies provide the spirit with interfaces, basically to different ways that reality manifests.
Next, add to that the concept of “transmigration” - which is that the combination of body layers you (you as sprit) can take on is changeable, and that the spirit can lose and/or regain one or more layers of being.
What if I left my physical body but kept all my other bodies? - this is what a ghosts is, imo. Similarly, you can get beings that took on layers of being but stopped short of going and getting a physical body, or they have a kind of energy body we don’t knw about, or they got a different kind of physical body, (like an animal or plant species, or an ET species).
Entities:
So because I believe that it’s possible that a spirit can have different kinds of incarnations including energy-body-only "incarnations) (I know, that not a good word for that really, given there’s nothing “carnal” there, but I haven’t thought of another yet.) then I also use that idea to allow for entities to exist that are sovereign, just like us, just not having the same configuration as us.
Thoughtforms:
But them I also see humans (spirits) as creator beings, and I use the animistic view that everything is spirit and thus everything has some level of memory and sentience. Which means that humans can create vessels such as astral thoughtforms, and that spirit is automatically present in these thoughtforms (or egregores if many people are involved).
Whether there’s enough to those thoughtforms to be self-aware and sovereign is a matter of complexity. As human contributors add to the thoughtform’s complexity it becomes more and more likely to become sovereign. But some of these, such as the gods that are things humans personified, (Mesopotamian cities like possibly Hadid - leading to the lord of Hadid, aka Ba’al Hadid, aka Bael for example) are imo egregores.
I actually think the “gods/demons/angels” that are ideas and natural forces personified or just invented out of need are the “best” gods. Created for humans and by humans makes them human-friendly and very helpful, while also being very strong from the massive input of human magickal oomph.
I tend to think many angels and demons (though not all, some are older egregores demonised for human political reasons) are ETs, pretty much all of them, but that’s me and a bit more out there, and borrows from the ancient aliens theory a lot.
So the ETs are much less predictable in friendliness, being real people not robots made to help humans. For these the relationship aspect be very important, where it’s not really for the egregores. But telling which is which isn’t always easy.
So I don’t use the concept of “dimensions” myself, because I’m happy with the idea of the system of bodies allowing access to different aspects of the energy of the universe, which is pretty much the same thing imo.
So portals are another thing. I think they exist, and that the physics of them is not well understood or known. I suspect there’s black project investigating them; we know the military has shown up at Skin-walker Ranch in the US to investigate the ones there. I’ve seen mild ones in operation in San Francisco and it’s said that part of the world and the Rocky Mountains in general have a lot of them. Sedona in Arizona, US and the surrounding areas are famous for them.
Personal portals that you make are a slightly different thing, imo, they are more of a mental tool, an thoughtform in their own right, so that they do not physically affect you (normally), they are astral-only. They act to create a connection between one place in the universe and another in your mind. I call them a tool as envisioning a portal isn’t required to do this, it’s an aide to this kind of working by taking advantage of human’s ability to visualise and create thoughtforms.
It’s a machine in the astral that makes evocation, (which is also astral travel between points in the universe) easier and more fluid.
Yes, from lesser entities, astral wildlife, parasites, human thoughtforms, the astral is a mess and full of things that don’t bring you anything very useful from spending time with them. If we had stronger senses then petting astral cats would probably be a lot of fun but most of aren’t there yet.
So my take on this, is, yes and no… that death is basically a transition between how many layers of being you are currently using. Dropping the physical body is “death”, but you are still around, as you still have all your other bodies, and most of your personality is stored within those other bodies - you still have your memory in the mental body, your emotions and your qi.
However that qi body si produced by and sustained from the physical body - no more physical body means the qi body slows fades until you die the 2nd death, as it’s put in qigong, and then you’re not a ghost any more. At this point the person normally sheds a couple more layers, and then puts new ones back on and this is reincarnation.
Here’s the thing, while the person still has a qi body they are a ghost and you can talk to them as any ghost.
But once they die the 2nd death then they are gone, and then yes, that’s when you summon kind of a copy of them built by you from the “Akashic records”. (The Akashic records is the name Edgar Cayce and co gave to the idea that all memory is stored outside of spacetime, also called “ether” or “spirit”, depending on your model.). However the universe being what it is and humans being creator beings, this copy can become a being in it’s own right too, same as any thoughtform. The thing about spirit is, it’s built to learn and experience, and it learns from it’s experiences, so it never stops evolving and changing.
I waffled on a bit more about my view of how incarnation works over here, and that thread also outlines the views of @HailTheOldGods which is different and cool, and I like the Nordic models a lot, so I recommend a read of that too. If you wanted to add your models in there that would be super interesting too.
Anyway that’s my 2c