Q1: Can humans distinguish between fact and opinion easily? Do they?
Perhaps, question 0 should be, can there be a difference, in practice, between the two?
For example, take the most fact-based community of them all, the scientific one. Earth was flat, earth is round. Light moves in waves, light moves in particles, no it's really both; electricity goes from negative to positive, no electricity moves from positive to negative, etc....
Many of these things were perceived as fact, yet false. The truth is, we never know 100% whether a fact is really a fact. A fact is a really dirty word in my opinion. Our senses, minds, and logic can deceive us, and the minute we think something is a fact, we are being very arrogant indeed.
One could argue that fact is opinion with proof. But then proof can invalidate itself too, just like opinions.
The word 'fact', implies a static universe, where truth can be static, with a non-relative reality. That's simply not how our universe works. (and that being an opinion too, we reach quite a paradox indeed )
So, what I'm getting at is, trying to implement methods to differentiate between fact and opinion is an exercise in futility (in my opinion ).
I'd go even further, and saying that sticking to perceived fact, and tuning out anything else, is diminishing your chances to discover that your perceived fact is incorrect, which is quite damaging to innovation if you ask me