Hi and welcome, Buckets. I'm one of the few Biblical devouts here who am confident in my own mind that it all has been eternally created, destroyed, & managed by an incredibly intelligent supreme Biblical god whose name is Jehovah. I've said that to say that so far as your questions, Biblicist creationists who aren't agnostics continually have and ask similar questions that you, the young agnostic are posing.
I've pretty much given up asking these questions since the bottom line is that the answer seems to boil down to something similar to how I must answer for my own hypothesis. The BB advocate and the evolutionist advocate, as well as creationists like me just don't know the answers to some questions in detailed depth. We all observe certain aspects of our hypotheses and base our belief system on what we think makes the most sense logically and scientifically.
It is the inadequacy of BB evolutionist in answering some of your questions which keep me in my own hypothesis and as well how my inadequacy to explain in detail how an eternal supreme creator can exist keeps them in theirs.
I apply the thermodynamic laws in supporting my hypothesis, though they see it as inadequate. Likewise I cite the problems they have in their application (or perhaps, imo, the lack of it) to their alleged theories (which I regard more as hypothesis status).
I guess what I'm saying is when all's said and done here, you'll learn some useful and interesting stuff like how relative the BB is to evolutionism, but good luck on conclusive answers to your really hard questions.
BUZSAW B 4 U 2 C Y BUZ SAW.
The immeasurable present is forever consuming the eternal future and extending the infinite past.