There are 2 questions in this :

A. I have deployed my code from dev Org to packaging org using workbench. For my code to work in packaging org, should my packaging org have domain name registered? I think it should because we need to include lightning out library in markup to enable us to use ltng:out as mentioned [here][1]

>Adding the Lightning Out Library to the Page
Enable an origin server for use with Lightning Out by including the Lightning Out JavaScript library in the app or page hosting your Lightning components app. Including the library requires a single line of markup.

    <script src="https://***myDomain***.my.salesforce.com/lightning/lightning.out.js"></script>

  [1]: https://developer.salesforce.com/docs/atlas.en-us.lightning.meta/lightning/lightning_out_markup.htm
 
I am a bit unsure about this. Please correct me if I am wrong.


2.If the answer to above is yes, then when this all is packaged in managed package and sent to some prod/sandbox org, for it to work there, it will require that org to be a.)domain name registered 
and 
b)Domain of that org has to be coded in above line. Does salesforce handle this automatically?


I know these are basic questions, appreciate your patience and pardon any silly asks.