1.Absence evidence the speed gravity must equal the speed of light. Mistaking of Kopeikin experiment in the year 2002; they measuring speed of radio waves from quasar, not speed of gravity. Nothing about planetary orbits would be completely unstable; because, actually, the force of gravity is the effects of well balance Universe.
In small scale, the force gravity is the effect of well balance mass. If there is no gravitational force in an atom; electrons will collapse as they run out of energy.
2.Between the two waves driven by gravity: i.e. Gravitational Waves and Gravity Waves, both can’t be true. Both can be wrong, but only one can be right. This is a golden rule in logic.