1) One who knows that he has committed a specific sin which is not explicitly mentioned in the viduy, should pronounce his sin with his mouth and say viduy about it with sorrowfulness of heart. If he has committed one of the sins specified in the standard version of the viduy, when he reaches that point he should feel very sorrowful. (Kitzur Shulchan Aruch 131)
2) The verse says “For the holiness pf Hashem is honored”, and we extrapolate from this verse that even on Yom Kippur where there is no eating and drinking, one must honor the day with fresh clothing and lighting candles. (ibid)