>>622733
We don't know for sure, but the antediluvian Earth was most likely very different than the current Earth we are living in now. For example, prior to the Flood, there may have not been any rain or storm systems, the antediluvian Earth could have been covered in a giant mist. We infer this because one of God's first signs He gave Noah from the Ark was the rainbow, which may not have existed prior to the Flood. Another hint could have been the construction of the Ark, the locals may have been mocking Noah not because of the location of the Ark, but the very concept of a boat in and of itself, but we really don't know for sure. Hope this answers your question as to a global flood.
>>622783
I believe all life on this Earth is recent 6,000-12,000 years old, but the Earth and the Universe may be much older than that. One hint is in Genesis 1:2 which already implies the existence of the Earth in a void state but God was simply terraforming it and creating life.