What are the repeatedly used structures in 4-character expressions (e.g. chengyu) and what do they mean? In today's reading, I encountered the expression 敬而远之.  However, I noticed this x而y之 structure is repeated in many other 4-character expressions (Pleco search ?而?之):
敬而远之
大而化之
等而下之
分而治之
换而言之
久而久之
取而代之
堂而皇之

Thus, it seems I should study how such structures work and thereby learn whole families of 4-character expressions at a time.
Question: What are the repeatedly used structures in 4-character expressions (e.g. chengyu) and what do they mean?
I'm seeking a kind of overview of major structures (those that occur in multiple 4-character expressions, like x而y之 above) for 4-character expressions, and a brief explanation as to how to interpret them.  It looks like x而y之 is an adjective that combines x and y.
Note that x而y之 is just one example, and there are others like 千x万y (see also Chengyu with two numbers).
(Whenever I look up chengyu on the web, I find pages like this and this which give a handful of common but disparate examples, making them very difficult to actually remember.)
It seems that there are two types of 成语 represented by the same “structure”.

A而B之 could mean “action + action, done to something (third person pronoun)”.

取而代之 means “to take and replace 之 (something that was previously mentioned)”. Compare this to 取代, which simply means “replace”. You could consider 取而代之 a literary form of 取代; using it adds elegance to an otherwise common word. Other examples include 换而言之、敬而远之 and 分而治之.

A而B之 could also mean “adjective + adjective, used to describe something (third person pronoun)”.

堂而皇之 means that something (之) is “wide like a hall and grand like imperial edifices”. Similarly, this can be considered a literary form of 堂皇. I would say 久而久之 has similar characteristics, but note that the 久 is describing a long period of time, instead of the appearance or a quality of an object.