Q3. (John 14:26; 15:26; 16:13a) Why do we believe that the Holy Spirit is not an impersonal force or power, but a Person?
I believe that the Holy Spirit is a Person because of what Jesus taught about him and how the Holy Spirit behaved in the NT times.
What kinds of functions that we attribute to persons does the Holy Spirit do?
Functions that we attribute to persons includes such description as leads, guides, testify, grieved, comforts, distribute his gifts to us according to his own will etc. All these functions shows that Holy Spirit is a Person and is different from Jesus or God the Father.
Why is it so easy to refer to the Spirit as “it” rather than “Him”?
It is easy because we cannot see the Holy Spirit and when the Holy Spirit works within us, it seems like a force.