John's Qualification for Writing

Read 1 John 1:1-3.
Which sense word does John use the most in these three verses: seen, heard, touched?
Look up "seen" in Strong's, the book or at www.tgm.org/bible.htm or some other site that gives you access to Strong's.
Does the Greek word that we have translated as "seen" mean more than simply observed, such as I have seen squirrels in my backyard?

How do these verses show why John is qualified to write this letter?
What does he say that shows he knows what he's proclaiming?
Why might John say that the deceivers aren't qualified?
Some of the deceivers preached that Jesus was only a man. How does John refute that claim in these verses?
Why is it important that "the life" was manifested to and seen by human beings on earth?
Why is it important that John is proclaiming these things to the believers in these churches where the deceivers were teaching?