I’m trying to see what the best & easiest method for bedding I can use in this new coop, in the pictures one of them shows a door that is used for clearing out bedding to add new, I want something not as dusty or as messy as wood chips. Any suggestions are welcome!

I see that you are a relatively new member with few posts. So, I hope to hear more from you as you get settled into your forever home. I think you have a great start on a fantastic chicken coop, just maybe a few changes for improvements as others have already suggested. No harm in considering the good advice from others. I find they are usually right.
I really liked that clean out panel. I wish I had built one of those into my chicken coop. In my case, I would have made the clean out panel to dump the chicken coop litter into the chicken run. But I never had laying hens before and had no idea of the value of using old coop litter as compost litter.
You already got some good comments to consider, but let me request that you add your geographic location to your member icon. I live in northern Minnesota, and what works for me might be different than someone living in southern California, for example. If you provide your geographic location, you will most probably get even better responses.
Anyways, I'll add a few comments to previous posts...
The roosting bars also look way too close together and those ladder type roosts don’t work well in most cases.
Yep, I thought of that too. From the picture, I can imagine the top chickens pooing the chickens on the next roost below. You want to make sure the spacing is adequate so that does not happen.
I don't think that top roost will get used, but if it does, it looks too close to the wall. You would end up with a very soiled wall board in no time. I'd certainly remove that top roost.
Depending on where you live, you might want to consider laying those 2X4 roosts flat. I live in a very cold winter climate, and having the 2X4's laid flat allows the chickens to tuck their feet into their body at night to keep warm and rest easy. That's why I mentioned to consider adding your geographic location to your icon. In the north country, I think laying those 2X4's flat is the best option.
I'd still use wood chips but in my case it's because it's the most cost efficient bedding (aka free).
I advocate for using any and all free material you can get. My favorite liter for the past few years is using shredded paper and cardboard. But I am not afraid to toss in and mix up some wood chips, dried grass, leaves, shavings, etc... Anything organic I can get for free and later compost works best for me.
Do you have lots of organics available to you on your new forever home location? Use what you have and then compost it and use it again!
x2 on the roosts as mentioned above. The top roosts are unusable because they're so close to the wall, and then every other board probably needs to come out or else birds will be pooping on each other.
Yeah, watch out for that.
We had to buy this prefab in a hurry! I’m so glad you said something. How would I go about adding some ventilation in here?? Just add some vents on either side up top? Or would putting hardware cloth over the windows for protection & opening them?
It looks like you have lots of windows. Can you just tack on some screen outside and leave some windows open? I only have two windows on my chicken coop, but they are on opposite sides, so I get good cross ventilation. Also, I have vents up in the roofline in the front and back. It's proven to be enough ventilation for me where I live. But I have more concerns about cold weather ventilation than ventilation concerns from heat.
But consider shredded paper for bedding. The materials themselves are usually free.
As mentioned, I shred almost all our paper products at home and toss them into the chicken coop as litter. The shredded paper itself is almost dust free, especially compared to the wood chips, leaves, dried grass, etc... that I have used in the past. Also, I compost all my old coop litter and the paper shreds compost faster than the other options.
Having said that, I have no problem tossing in other organics into the coop for litter as well. If it's free, I don't mind using it if I need more coop litter. BTW, the chickens don't care what I use for coop litter. I just try to keep it clean and fresh by cleaning it out twice a year. So far, that has worked for me, and I have never had to pay for coop litter in 5+ years of having a backyard flock.

As I get older, I appreciate the relative light weight of the paper shreds compared to wood chips, for example. I know you have a clean out panel, so it might not be a big deal for you, but I put my used litter into muck buckets and carry them out to my chicken run. The woodchips are much heavier than the paper shreds. I can carry a full muck bucket of paper sheds easily, but half a muck bucket full of wood chips is about all I care to lift. Again, I wish I had thought of a clean out panel like I see in one of your pictures. Very nice! Just shovel or broom out the old litter and put in the new stuff.
Will be looking forward to seeing more pictures when you get your chickens in the coop. It looks like you have a really nice setup started. Make it your own and let us know what works for you and your flock. Best wishes.