Understanding Case Lifecycle Report, Duration per Stage vs Age in Standard Case Report

We have a broad variety of very decent beers over here in Bavaria, dear Steve and all others. 

I am really trying to wrap my head around Standard Case Reports vs Case Lifecycle Reports. I do not have a specific goal, I basically want to understand whats happening in a Case Lifecycle Report and how to read them properly.

As a start, I wanted to find out how long it takes for us to close a case in Average. 

Here's what I did.

First I created a Summary Report

Filter: 

• recordtype = support
• closed = true
• (Picture1, Picture2 in pdf)

Report throws out an average of avg 6.581 days to close a case. 

Now, I went to the Case LifeCycle Report and created a Matrix Report

 Filter:

•  recordtype = support
•  closed = true
•  Rows: Owner
•  Columns: Status (also tried Case History Status)
•  (Picture 3, Picture 4)
•  

Here the average is 20.381 days, it only shows closed status. Not what I thought I'd get.

So I removed the closed filter. (picture5) Average is 19.385. No. :(

Then I ran the matrix report with open status only (new, open, in progress) (picture6) 

• The average of 3.821 kinda made sense... Although the filters were set above, I was very surprised to find 'Solved' as a column, too. 

From here, I stopped since I obviously started wildguessing.  

Here are my questions:

• How does my avg of 6.581 in standard report correlate to the matrix report(s) I built?
• What is the unit/metric of duration? Is it days? I know its buisness hours related but we got a 24/7 org. 
• We failed to establish a rule when/why a new row is added to a LifeCycle Report. 
• We assumed its  one row in Lifecycle for each row in Case History pertaining to Status or Owner Change. We checked - the hypothesis did not hold.  
  • So when does a new row appear in a life cycle report? 

  • Without this information, it is hard to understand the matrix reports or the report at all.
• In our Org the standard for Duration is Sum of Duration. I cannot figure out what SUM(Duration) might tell me from a business perspective 
• Why is solved showing up as status despite of the filters?

Cheers

Sz