Hi I'm +5 Years experienced C# Programmer, I have ample experience in Facebook Graph API, have done similar work many times in the past while I was developing Hootsuit type application for a client of mine.
I have read all of the 6 points and can make it as I have totally same work before, for comments specific purpose all we need to do is to call this edge of graph api post_id/comments.
Similarly all the information is retrievable.
Is this an existing application? if not then how about facebook oAuth to get User Access token and then access token of a particular page?
There are two types of access tokens long lived (expires in 60 days) and permanent (never expires)
Looking forward to working with you.
Regards,
Sohaib