(1) We have a vast experience of causes and effects. As such, it is rational to believe the first premise of the Cosmological Argument on our own experience alone.
I agree with Mr Jack. We know of quantum events that appear to be uncaused (ie their occurrence is genuinely random). The origin of the universe may be a quantum event of some kind, on the basis that we know there was a big bang. Therefore it is possible the universe as we know it had a beginning but is uncaused.
What preceded it, if anything? We don't know. It is possible the universe in some form has always existed. There's no need for God to break that particular chain.
Sometimes I hear arguments that God's existing eternally is different from the universe's existing eternally, because God is 'outside' time. But as far as I can see, any property you might wish to ascribe to God in this regard can also be ascribed to the universe. Why could not the universe (or the state from which it orignated) be outside time?
The KCA has no merit. As usual, with this kind of argument, it can only continue to exist because we don't actually know what happened. There's no evidence for it and no reason why anybody should believe it.