Q:

How to structure a multi object query

I have been stuck on this for a couple of days now and have scoured the internet for examples.  No luck yet!  
I have a question about how to structure a query that will return the data that is structured in the mockup schematic below.  
Right now I have a query that will get me all of the objects that are in the data structure, but the fields are referring to the top level object. ( Opportunity). 
An example is the Owner. Name is being returned as the Owner. Name of the Opportunity (Lisa Boyle), and not the Owner of the Account (Will Smith).  
Another example, the custom object Meeting__c CreatedBy. Name is also returning as the Opportunity CreatedBy. Name (again, Lisa Boyle) instead of the User who actually created the Meeting.  

My questions are:

How could I modify the query below, to return the correct data, versus referring to the Opportunity for the given examples.  

SELECT Opportunity. Id ,Opportunity. Name ,Opportunity. StageName, Account. Name ,Account. OwnerId , CreatedBy. Name ,CreatedBy. Email ,CreatedBy. Phone ,Owner. Name ,Owner. Email ,Owner. Phone,( SELECT Name,Scheduled_Date_Time__c,Is_Complete__c FROM Meetings__r) FROM Opportunity WHERE id = 'Xa11BBkl2jkl0024242' 

How would I add a one to many QuoteLineItems for QLI that are related to this Opportunity?  

A:

The general rule for SOQL queries is "5 up, 1 down". 
Querying data on related records
You can query up to 5 levels upwards in a hierarchy (e.g. Opportunity to Account is going "up" the hierarchy.  An Opportunity is only related to a single Account, but an Account can be related to many Opportunities). 
You can query up to 1 level downwards in a hierarchy (e.g. Opportunity to OpportunityLineItem)
Traversing up the hierarchy is generally easier to deal with.  You just keep tacking on relationship fields until you get to the object you want, and then end with the field name you want to query. 
e.g. Account. Owner. Name (when querying from an Opportunity) gets you the Name (field) of the Owner of the Account that the Opportunity is related to. 
You need to include the full "path" for every field you want to query on a related object.  If you want to include a lot of data from the Owner of the Account related to the Opportunity, your query is going to have a lot of Account. Owner.  in it.  There's just no way around that fact (I said it was easy, not that it was short). 
Querying down the hierarchy is a bit harder to write, and a bit harder to use.  This is where you use a subquery in the SELECT clause.  Something like
SELECT Id, (SELECT Id FROM Opportunities) FROM Account LIMIT 10
That second "SELECT" enclosed in the parenthesis is the subquery.  You need to use the relationship name rather than the object name in a parent-child subquery.  Usually this is just the plural of the object name (and __r instead of __c if you're working with a custom relationship field). 
The problem
In your case, there is no way to get all of your information in a single query (unless you've made some customizations to Quote/QuoteLineItem). 
The Meetings__c object is a child of Account in your schema. 
The QuoteLineItem object is a child of Quote (which you don't show in your schema). 
There is no single object that is the parent of both of those objects (without some serious customization), so it's impossible to query both and adhere to the "1 down" restriction that Salesforce enforces. 
The minimum number of queries you need to perform here is 2. 
The closest you'll be able to get is something like:

Perform an initial query on Quote so you can get access to the QuoteLineItem and Opportunity objects
Perform a second query on Account so you can get access to the Meetings__c object
Store the result of the Quote query in a Map<Id, List<Quote>> where the key of the Map is the OpportunityId
Store the result of the Account query in a Map<Id, Account> where the key of the Map is the Account's Id

You can then process the results in Apex so that you are able to tie the two sets of information together.  From the Quote, you can query Opportunity. AccountId, which would then give you access to the results of the Account query.