Is it permissible for me to favor certain jurisprudential opinions in matters of disagreement based on the evidence, even though I am not a jurist? And is my favoring of opinions in the matters of divorce mentioned in the question correct?

What you have understood is correct in general, and what you have chosen regarding matters of divorce consists of reputable opinions among scholars, most of which align with what is issued as fatwa on this website, so there is no harm in you adopting them.

If two people issue fatwa to you and they differ, you should ask the differing parties about their schools of thought and their proofs, then adopt what you find most convincing, if your mind and understanding are capable of that. Otherwise, it is permissible for you to follow the one you consider superior among them.

Your statement: "and there must be a firm intention (ʿazm)" - if you mean by it the condition of firm intention for a divorce to occur, even with an explicit statement, then this does not align with the occurrence of divorce from one who jokes or one who does not intend it.

It appears that you have some degree of waswasah (obsessive whispering). You should disregard it and pay no attention to it, and not preoccupy yourself with researching, reading, and delving deeply into the intricate details of divorce matters, as this will only increase the waswasah.