Yes, using Let’s Encrypt… the expirantion day should not be a problem, i had to do a fresh install this morning, so certificates will expire in 90 days.
Of course you are correct, but it would help if you included the proper way to do it - please update when you have the time; I’m sure it will help a lot of people, including me!
The proper way is to manage ownership & permissions properly, to the principle of least privilege. 777 is literally granting maximum privileges to everyone, which is may be fine as long as you have no other users and none of the programs you run have any bugs (spoilers: they do). Sorry, but a full explanation of Linux permissions would take more time than I am willing to spend. I am happy to give a hand up, not a hand out, so here are a couple links about why 777 is bad as a starter: