Facebook is very restrictive on what you are allowed to do with their API.
You can connect a bot to a Facebook Page or Profile. Normally connecting to a Page is better for automation. A Page bot can reply/comment to posts to the page, and auto post to the page.
A bot connected to a profile should be able to auto post, reply/comment to wall posts, a reply/comment to feed posts.
It is possible to automate more if you create your own Facebook app for your account. But this would require some customization under a Platinum account.