A few questions on the underlined sentence

The passage below is from A History of the Index by Dennis Duncan

What do we mean by an index? At its most general, it is a system adopted as a timesaver, telling us where to look for things. The name suggests a spatial relationship, a map of sorts: something here will point you to – will indicate – something there. The map need not exist in the world; it is enough for it to exist in our minds. Writing in the middle of the last century, Robert Collison proposed that, whenever we organize the world around us so that we know where to find things, we are in fact indexing. He offers a pair of illustrations that could hardly be more 1950s if they came wearing brothel creepers:

When a housewife makes a separate place for everything in the kitchen she is in fact creating a living index, for not only she, but all her household, will gradually get used to the system she has created and be able to discover things for themselves … A man will get into the habit of always putting change in one pocket, keys in another, cigarette-case in a third – an elementary indexing habit which stands him in good stead when he checks up in his hurry to the station to see whether he has remembered his season-ticket.

I have a few questions on the underlined sentence.

First, what does the bold-faced ‘they’ represent? I think it indicates people in general. Am I right?

Second, what does ‘if’ mean in this context? It does not mean ‘even though’ but mean ‘on condition that’, doesn’t it?

Lastly, the meaning of the whole sentence. It seems to say that the illustrations Robert Collison offer would exude just like 1950s atmosphere if people in the illustrations were wearing brothel creepers. Am I right?

Thanks in advance.