Carbonyl compounds: describe question

A student oxidises ethanol by heating it with acidified potassium dichromate($\ce{K2Cr2O7}$) and distilling off the product as it forms. The distillate is collected and tested with 2,4-dinitrophenylhydrazine (2,4-DNPH) reagent, giving an orange precipitate.

(a) State the reagent and conditions needed to oxidise ethanol to ethanal. (b) State the reagent and conditions needed to reduce ethanal back to ethanol. (c) The student adds hydrogen cyanide ($\ce{HCN}$) to the ethanal, with a trace of potassium cyanide ($\ce{KCN}$) as catalyst, and warms the mixture. State the type of reaction and the structure of the organic product formed.