Image preview + security

I would like to have the following done within 24 hours:

1- Image preview for Email + Linkedin + Facebook + Insta + whatsapp
- For home page -> same image as the slider
- For page about -> same image as home page
- For pages (that are post pages displayed in the menu): plastic & waste free ; permaculture ; thoughts ; tools -> image of the last post
- For contact page -> same image as home page

2- security of the website -> bring security level from middle to very strong
and explain to me what you did

Warning:
(1) if no delivery on time -> no payment
(2) if no full delivery, -> partial payment