Jackett can be run on any computer. It doesn't need a server or any serious hardware. It can probably be run on a $20 Pi. It's just allows you to interact with trackers via API calls.
I use Prowlarr via Docker now a days. It's provides a much better experience to interact with othe instances of ARRs.
You would reuse the same password or use the same password with slight variations. I would also often see passwords written down on sticky notes. People sometimes has different passwords but stores them unencrypted in password.xls or something similarly named.
Thank God for password managers these days. I haven't refused the same password for many years now. I generate three random words with a number and special character for all my passwords.