Because of the presence of only one alpha hydrogen , it's alpha hydrogen is very very weak acidic and so aldol condensation is slower than Cannizzaro's reaction.
First Geminal acid on heating undergo decarboxylation to formed 1,2-Cyclohexane Dicarboxylic acid, which is on further heating gives corresponding anhydride.
Chloral hydrate (CH3-CHO.2H2O) has unusual stability due to -I effect of three Chlorine atoms, which leads to the formation of two Hydrogen bond. The energy released in the formation of three bonds provides extra stability.