Be careful. In the BB theory, the universe has only existed for a finite amount of time. But, whenever there was time, the universe existed. In that sense, it has 'always existed'.
Wrong. There was no 'transition'. Non-existence simply does not exist. The universe does.
Just like there is no south of the south pole, there is no 'before the BB'. And, just like the south pole is not a 'transition' from non-existence to existence of the Earth, the BB is NOT a 'transition' from non-existence to existence of the universe.
There is no 'becomming', no 'transition', no 'before..after', no 'brought about by', etc. ALL of those assume that there was time, specifically a previous time. And, in the BB scenario, that is simply not the case. So language gives a poor description if you use time based language.
Sure, it is proper English, but that is irrelevant to what we are discussing. That 'proper English' assumes that there is always a 'before', just like someone might assume there is always a 'south'.
No, that is simply wrong. There is no 'preceding' because there was no time. The proper English assumes that there was.
They have to do with certain assumptions of language which may not be valid in this context.