translation - i am confusesd as to what historical present tense is, when it is used, etc

I understand that historical present tense is basically a tense that uses

"present tense to describe past events/actions more vividly and lively..." - Chocolate

Doing my own research into possible examples of historical present tense has only left me more confused as to what it is, how to use it, how to recognize it, the rules governing its use, etc...

1. 
   

   How can I tell if a sentence (or part of a sentence) in Japanese is written using the historical present tense?

   
   


2. 
   

   How can I tell if a sentence is NOT written in historical present tense?

   
   
   


3. 
   

   In historical present tense written in Japanese, are the past events written with past tense while the rest of the sentence is written in present tense?

   
   


4. 
   

   Should I attempt to translate the historical tense and put everything into present tense when translating from Japanese to another language?

   
   

   4.a. What tense do I use for the actual events when I don't know what said events tense type is? (うなずいて in the below example)

   
   

曖昧{あいまい}にうなずいてから, あと二人, 部屋の中に誰かいるのに気がついた.

Examples claiming to use historical present tense: "気づく" <- here, this stack question, and this one too, oh, and here

(If I had enough points I would create and use a historical-tense tag for this, but as I do not have enough right now, I am using the 'interpretation' tag for the mean time.)