1) Can an Account Owner see the details of the discussions of a Coach on their Account?

No, the Account Owner cannot see the details of a Coach's discussion with a Participant. Here's an example of what the Account Owner would see: 
The Account Owner would only see a headline/title of the Coach/Participant discussion and the date the discussion was created and updated (if applicable). Below is an example. 

2) Can the date the discussion was scheduled to be sent be changed?

Yes, you can change the date the discussion was scheduled to be sent. After you have created a discussion [in Knowledge Base see Discussions and Templates>Create Discussions], navigate back to the participant's discussion page and select the discussion. 

Select the pencil icon to edit the discussion. 

Next, select the "Discussion Date" box and you will be prompted with an interactive calendar to select your new date for the discussion to be sent. 

Select your new desired date and save the discussion.