In Esther 8:16, we read that after the Jews were saved from an evil decree, they had "light and gladness and joy and honor." Is anyone aware of Rabbinic texts that discuss celebrating Purim with candles or some other type of light?
ומצוה להרבות בנרות לפנות ערב, כדכתיב: "ליהודים היתה אורה"
It is a Mitzva to add candles in the evening, as it says: The Jews had light
He doesn't source himself and I haven't seen this anywhere else. It would seem he is using the word 'Mitzva' here quite loosely.
Yes, many poskim. The Kitzur Shulchan Aruch 142:5, Aruch HaShulchan 695:8, Eliyah Rabah 695:5, etc.
For more sources, see the discussion in the Nitai Gavriel on Purim, #70 http://www.hebrewbooks.org/pdfpager.aspx?req=46446&st=&pgnum=383&hilite=
Note, of course, that the rabbinic interpretation of that "light of the Jews" is in fact Torah study. Hence, no candle-type practice derived from that verse.
If I recall correctly one of the later commentaries on Shulchan Aruch -- the Pischei Teshuva maybe? -- mentions a custom of lighting candles for the Purim seudah, as it sets a more festive mood. I haven't seen this one in practice, but I could see why a custom involving open flames around lots of people who've had too much to drink would, well, fall into disfavor quite quickly.
SAFETY DISCLAIMER: If you're too drunk to tell the difference between "curse Haman" and "bless Mordechai", you probably shouldn't be playing with matches either.