If both inertial and non inertial acceleration are equivalent Then inertial & gravity time also equivalent?

Answer 1

I think you meant gravitational acceleration is equivalent to non-inertial acceleration. Morningfoxnorth's answer is good.
An interesting extension is that one way you could tell the difference between being in an elevator accelerating up in empty space and sitting on the Earth is to drop two objects, one from each hand. In the elevator they would be the same distance apart when they hit the floor. On earth, they converge, because they head toward the centre of the earth. But Einstein proposed that you CAN'T tell the difference between these two frames of reference. Therefore, they had to be the same distance apart in both cases. The only way for that to be true would be if space was curved! The lines of fall of the objects on earth are parallel! Parallel lines converge in the curved space around a mass.
So the idea that space is curved comes very simply from that equivalence you mentioned (the corrected version.)
-Cheers.

Answer 2

Yes.

If you are in a closed room with no windows, you can't tell if you are inside a spaceship accelerating at 1 gravity, or on the Earth at 1 gravity.

(Well, actually you could, because the Earth rotates, and you can tell that with a good gyroscope. But pretend that you're someplace with 1 gravity that doesn't rotate. Or, the spaceship rotates once a day.)

Answer 3

For inertial frame of refer. u can apply only special theory of relativity . General theory of relativity is applicable to both.