Pesachim 7: Finding the Right Words

Pesachim 7 - When on Passover Eve does the prohibition against owning chametz kick in? And what if you use the items that you would have sold during the time after that time - will it work? What changes with that moment of prohibition. Also, what should the language be for the blessing upon burning chametz? The discussion relies on biblical verses as possible ways of formulation - and the application here is unusual in unexpected ways (when the verses aren't being used to derive halakhah nor as an asmakhta/support). Plus: Light from candles vs. sun. vs. anything else. Candlelight is special... Or maybe not. Do we need to use a torch?