SSL stands for Secure Socket Layers. It’s a protocol that secures all communication between a client and a server; in practice that means between a web browser or mail client and the site you’re visiting or your mail server. It’s transparent to users, but usually denoted by a small padlock sign appearing in your browser.
Encryption is the process of obfuscating data into a format that essentially looks like a string of gibberish, were you even able to intercept it. A key generated on one end of the connection allows the software at the other end to understand and decrypt the information. This happens transparently and essentially instantaneously for the user.
The keychain on your Mac is method for generating and storing passwords and other login data in a secure format. If you use iCloud Keychain, Safari is able to generate extremely complex passwords and share them across all devices you have chosen to trust with that information.
Since encryption happens on your device, it shouldn’t matter whether you log into the cloud from your home broadband network or from your cellular device. The information is encrypted before it’s sent.
A recovery key is a string of characters that can be used to unlock an account when you have lost or forgotten your password. It’s important to keep it safe!