How does dedicated Server notifies Cliens about each other in p2p (TCP)

How does dedicated Server notifies Cliens about each other in p2p (TCP)

I am learning about network programming and I want to create a simple P2P
network based on TCP connection.
So far I have a server that accepts connections from clients (TCP).
Clients know about server's initial location.
These are my questions:
How can server notify clients about each other? is it the matter of simply
sending a list of every bodies IP addresses to everybody ?
If all clients are running on the same machine (eg 127.0.0.1), do they
need to use a different port number when connecting between each other ?
If I want to maintain a TCP connection, how do peers decide who is going
to be a client and who is a server in each pair? Perhaps this can be done
on server side when he is sending off information out to clients.
I assume that TCP connection is not ideal in this scenario, at least for
the reason that clients have to maintain a separate connection for each
peer in a network. Although this is more of a training exercise and I
looking for a reliable connection, where I don't have to deal with
possibility of some packets been lost/out of order. (at this stage:).
Thank you!