>>11 There is a link in each leaf to its parent. The maximum size of the tree is 65536 posts, at which point it stops being a single tree. A link to the top is not a useful concept.

Per default, the lastest 50 posts are displayed, but you can request any number or any subtree.

I think what you might like is to be redirected to a more distant ancestor than the immediate parent after replying.
(I would have preferred to send 201 Created, but then all browsers I have tested would only display your own post.)