Wow... Beautiful points to take home @didic. Sometimes, most of these errors are committed unwittingly while others are simply as a result of my not being sure of which to use at that point in time.
Sometimes I have to think it through and one rule I have cultivated over the years is that after I say it out aloud and it sounds right to me, then it definitely is right. That is how I made my choices especially in your third and fourth bullet points.
Thank you very much. Hemingway also helped me a lot especially to minimize the lengthiness of some of my sentences. I hope to do better in those aspects soon enough.
Gracias!