Way to sync Google reminders with the Mac ones

Keyboard shortcuts: Mail has it's own keyboard shortcuts, which you may have to learn.

Alternate email addresses/multiple accounts: works fine. Don't know about plus-addresses.

Priority inbox: this is not supported. Labels work, as does flagging. Public calendars work in iCal.

Syncing is very easy to set up - via IMAP in Mail, and in Preferences in iCal. In Lion it's even simpler.

Yes, you add each account separately in mail. You can still visit them in any browser or device.

I solved this issue by going to https://calendar.google.com/calendar/syncselect and unchecking my teammate calendar from the sync.

This is not totally fine because I cannot see my teammate calendar from Calendar but at least I can use it for my different pro and personnal calendars without being bugged by notification when my teammate are invited to an event.