I really recommend keeping an impression journal, if you don't do so already.
I'm not sure about your guides or angels or whoever that you are channeling, but my guides, one in particular likes to speak in multidimensional images(like super-download), and can take awhile to separate the nuances as well as the complexities of the messages. Plus it's fun to go back and read for inspiration. Another bonus is learning your own archetypes, there are universal and personal archetypes that can come across for myself at least during various messages, irregardless of the medium of communication. Learning your guides or channeled source's particular style is a plus as well, some guides like to send messages like packages, with practice one learns how to unwrap the gift intact.
There are several questions going on in your post so I'll break them down to their components to best answer them as I see it. I'm a beginner myself, so I apologize for the crudeness of my communication style.
Anyways, so it sounds like you got quite a few images and don't know what to do with the info you got. There's that integral question of trust. Sometimes it helps to, for a moment, suspend judgement. Okay, so for a moment, let go of whether the info is true or false, real or imaginary(unreal), the baby or the bathwater.
I think it's important to learn how to develop a relationship of trust with yourself first and foremost before trusting impressions gets better. So let's put a pin in that and keep the need to prove it suspended momentarily. And let's sit with the images, feel them, see them, openly, fully.....how do you feel? Do you have an attraction or repulsion to anything, look inside yourself, and take a gauge or litmus test. Use your emotions as your guide(like a compass). Write down your results.
So how to understand past live images....
Sometimes, I think many times actually, past life memories can be hard to validate. That's okay, and unimportant to the overall picture. What matters is what you get from it? Many times, when pastlive images first surface it's do to some sort of resonance in the current life one is experiencing. Just like how an event major or minor now can trigger a past memory from one's current life, similar events occur in relation to past live memories.
Also, many times(at first especially) these things that surface are old wounds, yearning to be healed. So these are things that best answered by oneself, but another person(either physical or non-physical entity ie. channeled source) can guide you. The benifets of working with non-physical guides is that they really have that golden touch to help in such a nuanced way.
Many times, for myself at least, with beginning channeling, it leaves one with more questions than answered, or as soon as one question is answered, ten more pop up. :P Plus sometimes, it helps to know what questions will help lead to further insight....so some questions that might be helpful to ask one's self in the path of discovery are: What was needed that didn't happen? What is the wound? What can heal it? Is there something in my life Now, that is occurring that reminds me of this? And what can I learn from it?
So, with all this past life stuff, what happens if you don't know your pastlife to clear your karma. Here's a hint: Now. All that matters is Now, in this moment, in the present. One doesn't have to know one's past life to clear any karma.
All one needs to do is not be afraid to look hard, and clearly at yourself in the present moment. Moment by moment, your life gives clues to your spiritual heritage throughout your life. Your emotions can be your greatest guide. Many times we are emotionally connected to our past lives, we can see this in how we react to the now. Your likes, dislikes, habits, revulsion. If there is something that we didn't like(or had trouble with) in a pastlife, we may choose to bring it forward in this life to work on it from a fresh perspective.
Many times, people get caught repeating, like a wheel, perpetually circling, round and round. I like to throw sticks at people's wheels, especially at those who spiral downwards, out of control. One can also stop the wheel from circling oneself. It sounds like you are at that point you are ready to shed the training wheels of karma.
Sometimes it helps to muster up all that feeling, passion, determination, and write down your power statement, this helps focus yourself, as well as bring power to your intention. It's important to write your statement in an empowering(positive), now context. Your guides want this for you.
To stop the wheel from spinning, all you need is a moment. Stop, look within, take a step back, suspend reaction, dig deep within. The wheel may pause for a moment, but what we want is to extend these moments, till the wheel just one day stops.
When things look hopeless we are at the greatest moment for change.
Okay, so I want to thank everyone for participating in this experiment(in the thread and at home), I'm going to go ahead and close it. I wish all the best and happy channeling!