@b3n @kallekn There even is a template-tag (you have to check the help in the top ride of the settings screen) but because Mastodon does not support inline images, they are added as attachments. But maybe Friendi.ca or Misskey/Calckey do support inline-media and it makes sense to use both.
The plugin does only support user profiles atm. there is no blog wide stream yet. So yes, it uses the gravatar image (or any other image, that is hooked into the `get_avatar` function).