3) Anyone who posts here is making random guesses.
Wrong. The times that posts are made are public and all of the posts (except in three subs) are public, so all someone would need to do is crawl all of the forum's threads and make a list of the times when each post was originally posted. There are several sites that are essentially mirrors of the forum so this has essentially been done multiple times before.
Might get the time during the day the most posts are posted. But I think the forums have a good amount off lurkers, and members not posting. So it's possible the most posted time of day does not equal most viewed.... we don't have data as normal people to say.
Also I would imagine top usage also has to do with attacks. It seems that sometimes forum get's attacked and has a slow down. These are not going to be easy to predict but if talking about most resources used it's likely during an attack. And that is just my guess I have no data to back that up.