Hello and welcome to the family, so great that you want to learn all you can since you have decided to add a grey to your life.
I have a cockatiel that I "rescued" since she just dropped into my backyard one day this past summer and no one claimed her so I kept her, she is not a cuddly bird either but she loves to fly when she is out of her cage.
I wish all other perspective grey owners would do the research you are doing before making that final plunge into owning one of these amazing creatures for they do require more than just a cage and some food.
Be sure to check out the book "For the Love of Greys" by Bobbi Brinker, I think it is the best book on the market for information about greys but be sure to read thru as many of the threads here for lots of useful info about all aspects of giving a grey what they need and want.
We have an other birds room where you can share a picture or two of Marble if you like, I know I would like to see him.