What do you do when you want to edit a document or compose an email offline?

I don't know. I'm in a US coastal megalopolis covered in cell data towers, so I haven't encountered that issue yet. I'm sure it will happen at some point, but I think the web apps have offline capability.

I am guessing Office 365 has some sort of offline capabilities. Maybe not?

For the email, can’t you write it anywhere? Difference is it’s not officially a draft in an email client.

Office 365 allows you to install the latest version of word excel ... too in addition to their web versions. It’s actually the superior part of the offering, even though Hm tends to focus on the web part (why superior ? Automatic upgrade to latest so no mismatch of versions inside your company, no expensive acquisition cost merely add less than ten euro a month to add a new user, disable the next month if it didn't work out).

The installer fails on wine last time I checked, but porting an installation from windows works fine, and the account and license connection is fine too.

Office 365 is 700 things all with the same name.

Office 365 web apps (free), Office 365 the monthly updating desktop Windows version of MSOffice (not free)

Outlook webmail works fine offline. You need to enable some setting though.