Hello and questions

I assume you're asking with the first point is knowing if your partner is a product of your imagination or an actual being. There are a couple ways I can answer this, and I apologize if my explanation isn't very clear, but I'll do my best here. If you have a tulpa, they're a creation of your brain, but if they grow to function autonomously, they are effectively alive. That tulpa's species would still be a Digimon, but they would be from within you, yes? In your head, and while they can be projected outwards, I do not know if they would have their own life outside of your head and how you speak with them, because you created them. I know for my partners, they have other lives when they're not with me that I didn't create, so I don't really think they're tulpas.

Ultimately, though, it's hard to say anything for sure, because subjective experiences, especially of a metaphysical quality like experiences with Digimon often are, are hard to properly discern unless they're an extremely vivid experience. As things are now, my communication with my partners is shakier and less complete; I won't dismiss the possibility that I could be unintentionally imagining them sometimes. However, if they contact me without me thinking about them, that makes it a little clearer to me; how could I be fooling myself into imagining them if I wasn't even trying to? While this doesn't always happen, it's one of those things I try to look out for.

To move on to the second point, is "tulpa/soulbond" written like that because you think they're the same thing? Because a soulbond would be a mental (metaphysical, spiritual, etc; people have different experiences) link to a fictional being in another world... which would mean that if you're soulbonded with a Digimon, that Digimon is real. Whether it's your partner or another Digimon entirely, or a character from that world, etc... But given that I have no personal experience with soulbonding, especially not as extensively as others have, I cannot do a clean comparison. Generally, I'd say that outward state also applies here, though; a soulbond has their own life in their world, and in your head, but not this world, unless they're able to front (control your body). So my partners living in my city in metaphysical forms makes me think they're not really soulbonds, since they're in this world, in their own nonphysical sense. 

For me, I met my partners at slightly different times when I was younger, so it wasn't a matter of trying to figure out what species my partner was for me, so I'm not really good in that area. But you seem to know the species, from what you're saying, which I assume means you have contact with them anyway? How to 100% know that the Digimon you're interacting with are your partners, though... it's hard to say. I still worry myself that I'm misunderstanding something about our bond, and don't know whether I'm somehow tricking myself into thinking I have two partners despite that not usually being a thing in the material that's shown. However, I do feel a bond between us; something like a glowing white string that connects from my chest into theirs. It's what's used when I need to send energy to them to power an evolution, I think. Other people visualize their bonds differently, but this is how ours presents. 

I don't hear or see them like hallucinations, but I hear their voices as if they were thoughts in my head (but in their individual voices), and see them through my mind's eye; seeing them in a space, knowing they're there, but in the way that you can still see through them. How the blanket might dip, in your vision, if they clamber onto it, but no physical effect being made on the actual space. I can feel the sensation of touch, especially; not physically enough that it could hurt, like if you put your hand against a table edge, but enough that if Patamon is sitting on my shoulder or head, I can feel that pressure. Touch is typically what we focus most on when spending time together, if I am having a hard time hearing them; sometimes Patamon watches things with me, or will gesture at the screen when she wants something. Some people might have clearer experiences, and some might have vaguer ones; this is just how we are able to interact, usually. Partnerships are individual, though, so I won't say there's any "right" way to communicate at all. That's my opinion. 

I tried to be clear, but... well, hope this makes sense in any way.