The DR number, Diederich Rank, refers to the highest number in Diederich's frequency listing, which you can see here: Diederich Ranking.
DR 114. Non nobis, sed omnibus. ~ Note: This is the motto of Soham Village College in Soham (Cambridgeshire), England.
DR 114. Non mihi, non tibi, sed nobis. ~ Note: This is the motto of the borough of Battersea in London, England.
DR 115. O si sic omnes! ~ Note: Even without a verb, the Latin expresses a wish: Oh, if only all (were) thus.
DR 115. O si sic omnia! ~ Note: Again, this expresses a wish even without a verb: Oh, if only everything (were) thus.
DR 117. Cuique suum. ~ Note: You need supply an implied verb to go with that dative: for example, Cuique suum (placet).
DR 117. Suo quaeque tempore facienda. ~ Note: Here is another use of that gerundive of necessity. The neuter plural pronoun, quaeque (everything), becomes the subject, and the gerundive agrees in gender, case and number: facienda.
DR 117. Sibi quisque habeat quod suum est. ~ Note: Note the independent use of the subjunctive, habeat: "let each person have..."
DR 118. post mortem ~ Note: This Latin phrase is often abbreviated: P.M. For more information about the use of this phrase, and the Greek phrase autopsia, see this Wikipedia article.
DR 118. Post mortem nihil est, ipsaque mors nihil. ~ Note: Note the parallel structure: Post mortem nihil est, ipsaque mors nihil (est). The words are from Seneca's Trojan Women.
DR 121. Age, si quid agis. ~ Note: Note that the quid here is functioning as aliquid (following si). This item is listed in Tosi, 933.