Clarifications wrt to nodejs as a beginner

Have just started to learn nodejs.

Have few clarifications to be cleared:

1) Have installed Node js in Ubuntu from this link: https://rainsoft.io/install-node-like-a-boss-with-nvm/

2) I understand that 'express' is a nodejs framework, and need to get the understanding of what exactly is 'express-generator'. Is the same like express?

3) From the above link, or from most of the links, its been said that nodejs is to be installed in the root or home directory(Ubuntu), Why only in this location?

4) I need to have my custom project, in /var/www/html/NodeDemo/ folder, how do i proceed:

To my understanding, it is like below:

cd /var/www/html/NodeDemo

express NodeDemo

How to start? Are the above steps correct?

5) How do i proceed to start the server and run a sample program in Ubuntu. Better if i get any link for CRUD program.

via Sachin S