I love a careful study and analysis of the actual text of Scripture.
I understand the methodology you suggest, but there is another important cause of variations to consider. Many of the variations are caused by Greek words that have very similar spelling. We see this in your second example from 1 Corinthians:
As you can see, they differ only by a single letter. So which explanation best fits the facts in this case?
1) A copyist erred on a single letter.
2) Two independent translators "just happened" to choose almost identical Greek words from the list of possible meanings of an presumed Aramaic original?
I tend towards Option 1 in this case. But it's just one example, and this solution does not work for 1 Peter 3:13 because the variants in that case are not at all similar in the Greek.
I very much look forward to examining more evidence with you.
Many blessings my scholastic friend!