The DR number, Diederich Rank, refers to the highest number in Diederich's frequency listing, which you can see here: Diederich Ranking.
DR 97. Actum ne agas. ~ Note: This is an elegant use of the Latin participle: do not do something that has already been done! Latin, of course, manages to say all that with just three little words. This item is listed in Tosi, 1114. Compare the saying cited by Polydorus in his Adagia, A83: Acta agis.
DR 97. Age quod agis. ~ Note: This item is listed in Tosi, 933. You can consider it an argument against multitasking!
DR 97. Agamus quod agendum. ~ Note: Note the subjunctive, agamus, "Let us do..." As for agendum, this is the origin of our English word "agenda," "the things which are to be done." As often, the relative pronoun "quod" does not have an expressed antecedent; it is only implied, as is the "est" at the end: Agamus [hoc] quod agendum [est].
DR 97. Aliter cum aliis agendum. ~ Note: This is one of the sayings Erasmus included in his Adagia, 3.8.58. It is another of those "aliud…aliud" sayings, this time with the gerundive agendum (see previous proverb): You have to deal with some people one way, and with other people another way.
DR 97. Aliter enim cum alio agendum. ~ Note: Here you see the postpositive particle enim in its expected position, indicating that the proverb is being used to explain something that has already been stated: The fact of the matter is, you have to deal with different thing(s) differently.
DR 97. Tuas res tibi habeto, tuas res tibi agito. ~ Note: This was a formula for requesting a divorce; both habeto and agito are future imperatives, commonly found in ritualistic expressions.
DR 99. Mors tua, vita mea. ~ Note: This is the ultimate zero-sum situation: it takes your death for me to live.
DR 99. Mors nec bonum nec malum est. ~ Note: You can find this sentiment expressed by the Roman philosopher, Seneca, in his treatise De Consolatione.
DR 100. Non sibi solum. ~ Note: This is an even more abbreviated form of the same idea, now with sibi as the dative and the adverbial solum: Not for oneself only. This is the motto of the Pike School in Andover, Massachusetts.
DR 100. Ego meorum solus sum meus. ~ Note: You can find these words in Terence's Phormio.