The order is user selectable via the button at the top of the thread labeled "last Post".
Jeff, I think it would flow better if a thread has the oldest (initiating) post first, followed by replies. Otherwise someone new to a thread has to go to the bottom and then read up.
Yes, as you can see here. There’s a photo selection on the menu to imbed one or make it an attachment.
Its not very intuitive: enter your discussion text first, save it, then select EDIT where you can add photos, links, emojis, etc..
Title says it all.