To my knowledge, yes. I haven't personally tested it (and probably should) but we had that written in. You would need to know the URL of any image you intended on using, but you should be able to edit everything. Just be sure to tap save once you do.

As for share the original content, no it does not. A link and we allow people to write their own description/reason for sharing a specific thing. Kind of like a resteem with many more benefits LOL at least when sharing to Steem. If you shared your Steem post to say twitter, it will have different specs, like the character count.