The DR number, Diederich Rank, refers to the highest number in Diederich's frequency listing, which you can see here: Diederich Ranking.
DR 151. Nihil vero verius. ~ Note: Compare the saying in the Adagia of Erasmus, 4.9.2: Vero verius.
DR 153. Multum legendum, non multa. ~ Note: Note the distinction between multum and multa: the goal is not to read lots of books (multa) but to read "muchly" (multum) - to read deeply, with understanding, fully, etc.
DR 154. Vide et crede. ~ Note: Compare the English saying: Seeing is believing.
DR 154. Quod video, id credo mihi. ~ Note: You can find these words in Plautus' Miles Gloriosus.
DR 154. Quod non legitur, non creditur. ~ Note: This proverb advises us that not seeing, but reading is believing!
DR 154. Non omnibus crede. ~ Note: Notice that the "non" does not go with the verb here, but rather with the word "omnibus" so that you could render it in English as "Believe not everything" (although that sounds a bit more odd in English than it does in the Latin!).
DR 154. Ne omnibus credas. ~ Note: Here the negating word is "ne," which means it goes with the subjunctive verb: ne credas, "don't believe."
DR 154. Non omni verbo credas. ~ Note: Notice here the independent use of the subjunctive as a kind of imperative - you should trust... but not every word!
DR 154. Non est credendum omni verbo. ~ Note: This proverbs shows the gerundive used impersonally to express a command: credendum - but non omni verbo!
DR 154. Non opus est verbis; credite rebus. ~ Note: The phrase opus est takes an ablative complement, verbis, while credite takes a dative complement: rebus.