For the second, Γάμος is like the word "marriage", meaning both the occasion of getting married and the state of being married. So a better translation would be "Master (your) marriage". Given the Ancient Greeks' dim view of women, I'm guessing it boils down to "Wear the pants at home."
For the third, I think it should be "Cause no grief onto [others]" (ἐπί+ dat.)
For the third, I think it should be "Cause no grief onto [others]" (ἐπί+ dat.)