ASK FOR AN IRREVOCABLE OFFER
Before you invest too much time and expenses, you should ask for an irrevocable offer, limited to a certain date.
You should be allowed to ask for any necessary information concerning the property as if you were the owner.
If necessary, you should be allowed also to set a building application.
For such an agreement you normally would not need a notarized contract.
But if you intend a greater investment, especially, if you intend a comprehensive refurbishment or development, this contract should be signed in front of a notary public.
Of course you need advice (not by the agent but by an independent consultant) how much time you need, to find out about the chances and the conditions under which you can develop the project.