You have a decision to make, my friend. Are you trying to write a novel for mass consumption, or a novel for a fairly narrow audience of historians? It's up to you, but I would put in enough historical content to keep the average layman up to speed with the significance of events as they unfold. The method you use to reveal this information is important too...but more about this in a moment.
3. I was told I needed to infuse my knowledge, findings, and interpretations into the book. What the person suggested was that I step out of the narrative and add my insights...Can't I have the characters do that for me. Speak my findings and interpretations?
That's your method right there. Honestly, there's very little in ANY story more boring than page-long paragraphs of narrated exposition, and the less of it you can get away with, the better.
No doubt you've already read Michael Shaara's Killer Angels. Shaara is masterful at delivering absolute REAMS of genuine history through the mechanism of putting you in each general's head as the story moves forward until, by the middle of the book, you understand why Pickett's charge was inevitable as the rising of the sun. Shaara uses a sort of stream-of-consciousness style to show the reader the internal struggle of Longstreet as he wrestles with two facts: One, he must give the order to attack the Union center head-on in the morning, over half a mile of bare upward slope, and two, that attack will not only fail, but will cost them the battle and quite possibly the entire war.
You can see how this approach translated to the movie Gods and Generals in the case of union Colonel John Buford, played by Sam Elliott, when he stands up and speaks Shaara's lines out loud:
"Meade will come in slowly, cautiously, new to command... And then, after Lee's army is entrenched behind nice fat rocks, Meade will attack finally, if he can coordinate the army. He'll attack right up that rocky slope, and up that gorgeous field of fire. And we will charge valiantly, and be butchered valiantly. And afterwards men in tall hats and gold watch fobs will thump their chests and say what a brave charge it was. Devin, I've led a soldier's life, and I've never seen anything as brutally clear as this."
That's a case of novel exposition carried straight on through to the silver screen...by putting in the dialog. When you put in exposition, put a lot of it in this way. Also,do it just enough to make it make sense. Don't show off your extensive knowledge just to show off.
And there's another point to make: If it doesn't contribute to the story, cut it out. Be brutal. The essence of the story is the story, the interaction of characters and the struggle and/or journey of the protagonist. That's what keeps peoples' attention...they want to know what happens next.
[Cue Forrest Gump voice:] And that's all I've got to say about that.
I am halt between two opinions on that right now. But I think I am going toward the Civil War buff. Not historians, for I am not one of those, but I enjoy the subject. I don't need much exposition.
That's your method right there.
Since I am the most comfortable writing like that, I will continue to do so.
Also,do it just enough to make it make sense. Don't show off your extensive knowledge just to show off.
Sage advice.
If it doesn't contribute to the story, cut it out. Be brutal. The essence of the story is the story, the interaction of characters and the struggle and/or journey of the protagonist. That's what keeps peoples' attention...they want to know what happens next.
Just worth repeating.