Is there a way to check if a special remote is setup to use GPG? And, if so, see the ID of keys that it is encrypting to?
You can tell this by looking at remote.log:
git show git-annex:remote.log
Remotes that are encrypted will have a big "cipher=" block in there, and ones that are encrypted to gpg public keys will have a list of the keys following "cipherkeys="
initremote myremote encryption=keyid