New to FBA hopefully here to stay

Hello everyone,
I am looking to source a product from Alibaba. I have found the supplier. I have discussed the pricing and shipping. I have calculated the profit, and everything seems to align.
I have questions about creating a new product, Amazon warehouse, and distribution services, as well as how to add a product I don’t have on hand.
Let me elaborate:
1. The product is chosen. All I need to figure out is my package’s design and size. Most likely, it will be a large or oversized product. The product itself is pebble-like soil(not considered actual soil)
2. I do not understand how to calculate what I need to pay for storage and distribution services as I am still in talks with the supplier about sizing and package design. I do have a GTIN that will represent my product, but I cannot add images yet. I can not create and verify the brand with Amazon for my product either.
3. For the supplier to give me an accurate estimate for shipping, I need to give them the address of the distribution warehouse, but…. Amazon will not give me that until I verify my brand, upload my product, and give them all the other details.
If you have any suggestions or are willing to engage in a discussion, I would love to hear more from people who know what they are doing.