The best resource I know about, for understanding the Prophets, is an old radio series that Fr. Mitch Pacwa did, The Old Testament Prophets. (You can most easily download it as podcasts from EWTN’s Audio Library, but there’s also a version on YouTube that somebody augmented with picture stills.)
Fr. Pacwa used to be a college professor up at Loyola in Chicago. The series, The Old Testament Prophets, is basically his college course – if college classes only lasted 25 minutes or so. (And since it’s OT prophet stuff, I don’t think you’ll find much difference between Catholic and Protestant interpretations. If it was a course on the wisdom literature of the Bible, maybe not so much.)
It’s very long (59 eps), very thorough, and very easy to understand (if you start from the beginning). He talks about all the stuff you’re interested in: the history of Israel and Judah, the weird imagery, and even what the heck a prophet was and did. If you just listen to the introductory episodes, you will get a lot of knowledge. If you listen to the whole thing, you will have a really good grounding in these books!
The prophets are our friends and teachers, no matter how long ago they lived. Don’t worry; you can get this!
Re: lack of understanding, you know that grace usually builds upon nature. Like the Ethiopian eunuch on the road said to St. Philip, how can you understand unless you have a teacher? Obviously God could just teach every baby to speak like a Shakespearean actor as newborns, which would save a lot of trouble on understanding cries and learning human language. But usually, He wants us to learn through practice and failure, study, memory, discussion, and chewing things over in our own thoughts.