Yes, gravity is equivalent to acceleration, and acceleration requires energy, and energy is interchangeable with mass. Therefore gravity is material, even if we still lack a complete description of its attributes.
There I cannot agree with you. Just because a theoritician has proposed a particle called a "graviton," does not mean it exists. We have never observed one, have no idea of how to obseve one, nor do we have any theory as how a "graviton" can work at stellar distances.
All measurements of gravity is in some way "calculated" whether by an analog device such as the stretching or bending of a spring or by the finding of a zero point by trial and error of a balance scale. None of them measure gravity directly, they merely measure its effects.
Until we can find your graviton and describe how it works, I doubt we will be able to directly measure it.
Einstein proposed that gravity is a multi-dimensional bending of space-time relating to the presence of mass.