I will for your second query venture
Esto aliis benevolus.
(This would be addressed to a singular masculine entity).
"Be true to yourself" is difficult, not to say controversial; the question has arisen in this Forum on at least two previous occasions. In many places on the web one finds Tibi ipsi dic vere, literally "Tell yourself the truth". But no one has been able to cite an authoritative source for this, or to connect it with the concept of being true to oneself. I fear it may be another example of what I call "web-Latin". My own translation of the phrase?
Esto tibi ipsi fidus.
(Again, singular and masculine).
Hope this helps.