You'll need to read up on the big bang theory for yourself, I'm afraid. I can't do all the work for you.
When do the answers start?
I have no idea what a "sea of gravity" is. It sounds like a term you just made up.
Yep! Like photons, gravity does not suddenly vanish at X distance from an object. What it does seem to do is become mixed so non-directional below a certain value. We can detect single photons but have no method for detecting single "units" of gravity on the same scale, so it's like detecting where waves come from in a stormy sea. We can only detect the tsunamis in mid-ocean.
Yes, but it still slows it.
But not really a need for dark energy as the universe would automatically expand faster as it got bigger.
No. How could the expansion get faster, with gravity always pulling it back? Even if gravity gets weaker as the distances increase, gravity remains always an attractive force.
Gravity is pulling over ever greater distances, so weaker. It is also hampered by light speed.
There's firm evidence for the big bang theory. Lots of it.
There are set interpretations of certain evidence. There is strong evidence against the BB too which is usually blatantly ignored and pooh-poohed.