My personal belief on this matter is that proximity does play a role in everything you mentioned, but the answer to your actual question of "do they have to be close" is a definite no.

My understanding is that the more powerful of a connection there is between two beings, the more energy can be passed between them. Like working with almost anything in our physical realm, the larger of an effect you desire the more energy it requires to power that effect.

So, in my opinion it would be considerably more difficult to contact someone you are unfamiliar with than someone you are. Then, it would be more difficult to contact someone you are familiar with when they are at a greater distance away, and easier if they are close. I believe there are many factors that determine the relativity from the source to the target other than proximity and the bond between them, and they all come together to determine the actual outcome.