Hello Michael,
I'll do my best to answer all of your question. I was able to find the following article in our Resource Center that says:
"The call from which the callback request originated is not included in abandoned calls count. The callback object placed in the queue takes the position in the queue of the original call and automatically acquires the same skill requirements and priority settings as the original call. "
I'm not 100% sure if there is any sort of report that you could create to track those missed interactions but agent could schedule a callback if they need to follow up with the customer.
With regards to ASA, I do not believe that callbacks are factored into the equation since ASA is influenced by the average length of each call, the number of agents who are available, and the total number of calls that are arriving, though callbacks would affect the Handle Time.
And to answer you your last question, any callbacks are associated with the original interaction. If you have not done so already, I would recommend checking out the following Resource Center article:
https://help.mypurecloud.com/articles/schedule-a-callback/
I hope that helps answer your questions!
------------------------------
Jason Kleitz
Genesys - Employees
------------------------------