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How do I look up commentaries on general patterns in torah as opposed to specific verses?

This is a research-methods question with a concrete example.  I'm interested in the answer to the concrete example, but what I really want to know is: how could I look this up myself?

There are sometimes widespread patterns in torah.  For example, I know about the reversing *vav*, which flips a verb from perfect to imperfect or vice versa.  I know this happens all over torah, and I know the torah uses the "regular" perfect and imperfect verb forms in many places.  When the torah uses one of these approaches consistently in a section, that doesn't seem particularly remarkable.  But I came across a case where both forms are used in the same passage: in Bereishit 22:20-24 the torah uses both יָלְדָה and וַתֵּלֶד.  The commentaries I found there don't talk about this, but if this is the Nth occurrence of that sort of thing, why would they?  All I can tell from the absence of commentary is that there's apparently nothing special specifically about contrasting Milkah and R'umah.  But that doesn't get me any closer to my answer.

If I had a question about specific words, I could use a concordance to find the first occurrence and look there.  If the words were uncommon enough, I could even look up all the occurrences.  But, short of reading from the beginning, I don't know how to find the first occurrence of both of these verb forms in close proximity.  And maybe I'm thinking about it all wrong; maybe I shouldn't be looking for commentary anchored to a specific passage when it's something widespread, but should instead be checking somewhere else.  But where?

How do I learn how to learn -- how to find commentaries about "meta" issues when I come across an instance?