Where to store passwords for backup scripts?

Question

Backup

Good afternoon.
Tell me, how to organize backup correctly in terms of password security?
Now my copying goes through the crown, the bash script is launched, in which the login and password from windows balls are registered, the login and password from the mysql server. The script itself is in /usr/local/sbin . Actually, the script backs up the mysql database, connects the ball to the windows machine and throws the archive there.
I have 2 questions
1. - Where is the best place to store passwords and the backup scripts themselves
2. - How can I organize log rotation with this approach? (I mean, which machine, ideologically correct, should keep track of this? storing logs, or creating them?