Are the names: The Granter of Benefit, The Inflicter of Harm, The Bestower of Honor, The Abaser, The Equitable, among the Most Beautiful Names of Allah? What are the proofs for that, and has a sound hadith been reported that collects them?

The Beautiful Names of Allah are fixed (tawqifiyyah). The names mentioned in the question were reported in a weak hadith by Tirmidhi and Ibn Majah. There is no authentic evidence from the Qur’an or Sunnah that proves them. Although the Qur’an informs us that Allah honors (yu'izz) and abases (yudhill), benefits (yanfa') and harms (yadurr), this information does not mean that a name for Allah can be derived from it.