Nextcloud notes. They’ll sync as text filed between your devices. You can use markdown, and they have a mobile app.

Yeah but the majority of bots out there are going after easy prey. Honestly, if you use public key authentication with ssh you should be fine, even if it is on port 22. But it does of course clog up access logs.

Https and a server. If hosting at home just leave a high numbered port open. If on a vps then you should be able to use any port you want.

I’ve managed to do it for my personal email and find it very rewarding. Sadly, I could never use it for my business. It’s just too risky and there may always be a few delivery problems here and there.

VPS hosting, BTW, not home.

Frankly the only thing I’d save in Google Docs are encrypted archives. Otherwise they’ll profile the documents to send ads to you. But it is a good back up in case lightning strikes your home or something.