Please help me regarding usage of W3 total cache and yoast SEO plugins in wordpress for optimization and performance of website.
What kind of help do you exactly need?
There is an extenstion for Cloudflare at W3 Total Cache under options which you can enabled, if you use Cloudflare for your domain.
There are topics about it, moreover, I believe you would need to follow the steps as written in the article below to achieve what you want:
Regarding the security, you can setup bunch of them to protect your WordPress, for example wp-login, either from brute-force, lock-in for specific countries and block everyone else accessing it, you can enable
Bot Fight Mode, etc.
Here are few:
Due to WordPress security, kindly make sure to read and apply the recommendations from this guide:
Moreover, install some firewall/security plugin as follows here:
Thanks a lot dear. I will apply these settings on my website as and when I got time.