Q #3: When someone speaks in tongues, do they know they are doing it or does it makes sense to them?
This question asks about the mechanics of speaking in tongues. What's happening when a person speaks in tongues? I think that's the heart of what is being asked.
First of all, speaking in tongues is a matter of the conscious will. It's something a person has complete control over. That's why 1 Corinthians 14:13-15 says what it does:
For this reason the one who speaks in a tongue should pray that they may interpret what they say. For if I pray in a tongue, my spirit prays, but my mind is unfruitful. So what shall I do? I will pray with my spirit, but I will also pray with my understanding; I will sing with my spirit, but I will also sing with my understanding.
While speaking in tongues is a conscious experience--I know what I'm doing and can stop or start it at will--it is not a rational experience. That is to say, I don't know what I'm saying. I am giving words to what the Spirit is doing in my heart or spirit. So, speaking in tongues is aptly called, "praying in the spirit" because it is something happening at the level of the spirit, not of the mind.
We can also understand that this kind of speech could be sung. Beyond that, praying in the spirit, because it is prompted by the Spirit of God, is prayer that happens in perfect accord with the will of God. Things we don't know to pray in our conscious, rational self can be prayed for, interceded for in the supra-rational spirit!
Now whether speaking in tongues is an actual language spoken somewhere in the world, that's a question for another post!