Basic Networking Issues - Guidance Required

Hi, I have been trying to simple networking in which i can send a message from one device to another. My first thoughts were ‘Would I have to pay to use unity multiplayer functionality?’ so I found this [article][1] which seemed clear and directly explained how I would need to do networking in order to maintain zero costs on my behalf. After further searching I discovered [this][2] bit of unity documentation which seems to explain how to do networking simply in the same way described in the previous article and eluded to simple message sending which I desired.

But I have seemed to ground to a halt in this journey of discovery as I have found no further articles or videos to guide me and answer my questions which i still have about how this works.

Hence today i am asking :

A - Do you know of any further articles or videos which would guide me through this?

B - Am i going totally in the wrong direction?

C - Could you answer any of my key questions as below?

  1. When creating a server, i.e below, what port should i listen on and should I worry about ‘port forwarding’ which is a phrase I see often chucked about.

NetworkServer.Listen(4444);

  1. When creating a client, i.e below, what i.p address should i use? I presume it is that of the client’s device but how do i know what it is?

myClient.Connect("127.0.0.1", 4444);

  1. How do i get 2 devices to connect, my idea was to make any device by default become a client and then somehow ‘check for servers’ and if not it would create its own server with local client for a client to connect to, this way there would be no excess servers… ?

Thanks you very much for reading my question and I hope it seems clear, please check the links so that this will make sense to you. Any answers are greatly appreciated so that i can continue on my journey of understanding.
[1]: c# - Can I use the Unity networking HLAPI without paying for the Unity Multiplayer service? - Stack Overflow
[2]: https://docs.unity3d.com/Manual/UNetClientServer.html

An answer by the person who made the stack overflow article i linked can be found here -
http://stackoverflow.com/questions/38673176/unity-client-server-basic-questions