Does iCloud photo sharing able to share photos in full resolution?
Or do I need to create a group in iMessage then send all the photos manually?
But pictures get compressed when you send them in iMessage? But they should get the full resolution from photo sharing, seeing as that is one of its features really.
Nope. But it does get compressed i think if you're in 3g
What? So iMessage will determine whether to compress it or not if you have 3G or 4G (wifi and above)?
Yes. If you're the receiver of iMessage pictures. Why don't you try it?