Thank you for taking in and rescuing this poor bird from such an awful environment.
Sit back, relax and get ready for many wonderful years of learning about your new addition and enjoying his company.
I'm going to steal something I wrote on another introductory post as I think it may be helpful here: "One thing you will learn quite quickly is a little thing called "grey time". This is the time it takes for a grey to adjust and accept changes. This can be changes in routine, toys, location, people etc etc. Your bird has just undertaken a very big change and everything is still very new. Your bird is trying to adjust to a new home, new humans, a new routine, new sounds, new toys... everything. This can be a bit overwhelming for a grey as they can be a little change adverse at times. It can take days, weeks or sometimes months for a grey to adapt to these kind of changes and come out of their shell. This is what we call 'grey time'. Some changes may be more readily accepted by the bird than others... so there's no telling how much 'grey time' is needed for different changes. The important thing to remember is that the grey will show you when they are ready to accept a change or a new offering. They will also show you when they are not ready. A lot of this is shown via their body language- so pay attention to what your grey is doing... especially if you receive a nip or a bite...e.g what were the eyes doing, how were the feathers being held? There may be some subtle signs that your bird gives you before he resorts to a bite. Given enough time, you will start to be able to read your birds body language and will be able to know when the bird has had enough or is happy to progress."
Allow your bird time to settle in and get used to the comings and goings of his new home. Talk to him often, tell him what you're doing, tell him why you're doing it. Maybe read some books to him or ask your children to read to him. This helps him get used to you being around him and gets him used to all of your voices.
He probably doesn't like the dowel rod because he's never seen it before and it's coming straight at him. He will probably bite it in protest of it coming near him. Again, it's going to take 'grey time' for him to get used to it.
There is a massive amount of information on these forums available to you so please feel free to look around and use the search tool. If you don't find an answer to your questions then ask - someone will be able to help out.
In regards to vets- ALWAYS take your bird to an avian vet. Never take them to a 'regular' vet who isn't qualified or trained in avian care. They won't necessarily know how to handle your bird or treat him and this can lead to unnecessary stress for the bird or incorrect advice being given.
I recommend looking into what foods are/aren't safe for your bird. Start giving him some different choices of foods. It may take a little while to wean him off a purely seed based diet but do persevere. He'll find something he likes eventually!
Lastly, we like photos. As and when you're able to, we would love to see some photos of your new feathered friend.