>I am a very avid reader

I never understand what is a "avid" reader as redditors use the word. But nevermind it.

If you want to write a fan letter or communication, just do, if authors do not want it, they can not check their mails or whatever (and some do not).

But keep something in mind, sometimes it might be disappointing to know too much about the authors, and it might affect how you enjoy a book. A quote from a favorite book of mine

“Despite the fact that he loves books and owns a bookstore, A.J. does not particularly care for writers. He finds them to be unkempt, narcissistic, silly, and generally unpleasant people. He tries to avoid the ones who've written books he loves for fear that they will ruin their books for him.”