Understanding the layers in a citation

Dear Editor;

I've read over various portions of the EE book (3rd ed.) and still am trying to come to terms with the overall purpose of each layer in multi-layered citations. This has been bothering me for a while, but I need to get this straight in my mind. My apologies, in advance, for the long posting.

Here is an actual example, crafted from my research, which I hope can be used for discussion purposes. It is based upon the QuickCheck Model, "Digital images - International Censuses (U.K.)". For the benefit of readers, this is found on p. 240.

Source List Entry:
England. Kent. "1901 England Census." Database with images. Ancestry. http://ancestry.ca/ : 2018.

First (Full) Reference Note:
"1901 England Census," Kent, Brenchley, p. 10 (printed), schedule 71, Frederick William Wells (age 34) household; image, Ancestry (http://ancestry.ca/ : accessed 10 December 2018); citing [The National Archives of the UK (TNA),] RG 13, piece 760, folio 75, page 10.

Subsequent (Short) Note:
"1901 England Census," Kent, Brenchley, p. 10 (printed), schedule 71, Frederick William Wells (age 34) household.

Let me describe what I understood to be the purpose of the layers (as delimited by the semi-colons) in the first full reference note and ask you to confirm or correct my understanding, as required. I will add my questions / clarifications in parentheses, after each statement.

- The first layer is viewed as if someone had placed the work (e.g. a book) I'm citing on the desk in front of me. I'm trying to clearly identify the overall work itself and where in that work I found the item of interest.
(Now, keeping in mind the item of interest is contained in a web-based image accessed via some form of database ... Can I draw on information that is not explicitly in the image, but is contained in the database entry associated with the image. In this sense, I'm considering the database to be akin to the index in a book and the image is like a figure referred to from within the index.)

- The second layer recognizes that the book is not physical, but a digital image that is located on a particular website owned by Ancestry. Having described the book and the item of interest, I now need to document where it can be found.
(This is analogous to viewing a particular edition of a book as only being available at a specific library. One has to tell the reader where to find that exact edition. Is that a reasonable way of looking at this?)

- The third layer is important, because it documents the origin of the image. The characteristics of that image may influence the assessments that are based upon it. (If the image were a picture from a war, the photographers allegiance might influence the way the same physical event is portrayed. That would affect any analysis of the event, which was based upon the image. In a census, the quality of the image may result in some details being clearly visible ... or not. That could affect our ability to reliably extract information and influence our decisions.)