Emma - I'll try to give you some insight... at least from where I see it.
Prophecy is a gift from God, and our God is perfect - He never makes mistakes. However, His children do; Jesus scolded the disciples, saying, "Oh, ye of little faith." Peter stepped out of the boat and walked on water, toward Jesus - but, as his faith ebbed, he began to sink. His "ability" to walk on water hadn't faltered, Jesus' capability to supply Peter's need hadn't faltered - Peter's faith had faltered. Jesus said, in Mark 9:23, "If you can believe, all things are possible to him that believes."
A word of prophecy from God can look forward. It can also be given as an insight to an individual or situation, possibly revealing God-given information to that person. Obviously, such "forth-telling" is not equivalent with Scripture - and that's why such prophecy should be tested - by its conformance to God's Word. I Cor. 14:29 says, "Let the prophets speak two or three, and let the others judge."
Emma, only God (and His revealed Word) is infallible...
Charismatic Christians must admit that the excitement, the joy that the Holy Spirit provides can be the catalyst that draws people to charismatic churches. OF course, this is good - it's drawing people to Christ Jesus, which was the purpose of the baptism of the Spirit (Acts 1:8). On the other hand, it can motivate people to seek the experience, seek the gifts, and not the Giver of the Gifts. This will end up in disappointment, in envy, in frustration.
This was my experience, for several years. Frustration, crying out to God for the filling of the Spirit, instead of focusing on Jesus. But once I received the baptism, I finally felt the "internal, personal, soulful, peaceful experience of the Holy Spirit," as you so eloquently put it. I don't know... thirty years in Baptist churches, and a superficial relationship was all I'd ever known. God gave me a hunger (in my immaturity, I see now) for tongues - I never realized that with HIM I'd get the joy and peace that I'd been craving, and not just from "tongues." This hunger led me to seek the gifts, and by HIs mercy He gave me the fullness of His Spirit. Afterwards, I received my "prayer language," but my hunger was satiated by His presence.
So to try to answer your second question, the "charismatic pre-occupation" with spiritual gifts may just arise from the joy that He gives us as we worship Him - in part using these gifts.
I don't know for sure... just my two cents.
May God richly bless you.