Points of view/periods of time question

I have a few questions. I'll try to ask them in a way that makes sense.

How can I differentiate between two people and three different periods of time?

I am writing my fathers story, which is based on the letters he wrote to his folks during WWII. That is one section, the letters. Then, I have interviewed him about the letters and have another section in which I explain situations referring to specific letters. And the third is my memory of growing up. Upon writing this, I realize that there is a fourth, and that is the present time, when we get together to talk about the letters.

Right now, the way I am working it is this; The letters are in italics; I start off each conversation that Dad and I have regarding them with a sentence like, "We sat down and opened the notebook." My hope is that this way the reader knows where I am; I put five stars above my memories. Is that enough, or will the reader just be entirely confused? Each chapter, by the way, would have several of each "section."

Another question is this; My father had a breakthrough after reading a book by Tom Brokaw. Can I write about this without his permission? It is a very important part of the book.

Also, how many words is acceptable? I have read that between 50,000 and 80,000. Is that about right?

Thank You,

Lavinia

Thank you. I'll just keep with what I'm doing. I think it might help if I print off a few chapters and read it like a book. Maybe then I will be able to see if it flows. I don't know. I feel like I'm too close to it to see it objectively. I could also give it to a non-writer friend and see if they can follow it.

I like your idea of contacting Tom Brokaw and I know he has a heart for what I'm writing about. But I wonder how open someone like that is to an unknown like me. Seems like my book would never get past his PR people. But it's worth a try. I would want to use a paragraph out of one of his books. It is key to a turn-around for my father and his steps toward healing from PTSD.

Anyway- thanks for the encouragement. You helped to get me thinking more about all this.

Lavinia