Can a hacker hack a website's FTP, SSH and/or .htaccess file?

Can a hacker hack a website's FTP, SSH and/or .htaccess file?

I know that a website can have some vulnerabilities that hackers could use
even though the admin tries his/her best to make their website very
secure. I want to make my website secure and by doing that I need to try
my best to do so. First way to make it secure is to ask questions and
below are the specific questions I want to ask.
These are my specific questions:
1. Can a hacker access my website's .htaccess file? And if so, can they
edit it?
2. Can a hacker get my SSH root password even if the SSH password is 18+
characters long?
3. Can a hacker get my FTP username and password even if the FTP password
is 18+ characters long?
4. Is SSH more secure than FTP?