Your username here MUST MATCH your XenForo username (connected to your XF license).

    Once you have registered here, then you need to start a conversation at xenforo.com w/Bob and provide the following:
    1. Your XenForo License Validation Token
    2. The Domain Name associated with the License
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Comment box

There isn't an option to do that. It would require customization (Template modification and Programming modification).
Industry Standard. Comments systems have always been newest comment on top with the input box above the comments. Discussion systems (Threads) have been just the opposite (input at the bottom with newest post last). The top Comment system on the internet (DISQUS) follows this industry standard (input above the comments) with comments sorted newest to oldest. Even the Facebook comment system that is a close 2nd to Disqus has the input at the top.