What should be done before uploading HTML 5 template to hosting?

Question

CMS

I downloaded the HTML 5 template, corrected it for myself with the help of Denver and the editor.
1) What checks should be made?
2) Do I need to "pull" it on different CMS?
3) What is HTML 5 and what is it eaten with?
4) How to make it safe from hacking
It's just all so unusual. I used WP before and did not particularly delve into the subtleties.
PS I did not find the necessary answers on the web

Answer 1

What checks to make?

W3C standards validation:
HTML: https://validator.w3.org/
CSS: https://jigsaw.w3.org/css-validator/

PS I did not find the necessary answers on the web

Who thinks the same - don't like!)

Answer 2

it's just an html template.
none
if you write that you have already made it for yourself. which means it suits you. apparently you can not pull
htmlbook.ru/html5
it's just a template. there is nothing to hack

Answer 3

What's difficult? I made a backup of the host - uploaded my creation - does not work - rolled back, and so on until victory)