I do this and I use it with Aerc & Notmuch with Mbsync. It works awesome, downloads all my mail in maildir format, indexes encrypted mail which I can search the body of also (because Notmuch can do that), and also get ability to use tags, like Google mail. I use Syncthing to sync it to my server.
Yes that does work. It supports curve25519, and you can use a separate keypair for Guard. Guard requires private key as well though, but you can use a different key for inbox encryption.