What did Napoleon announce? What was the penalty for not volunteering?
That there would be voluntary work on Sunday afternoons. The penalty was that if an animal should decide not to show up he/she would have it's rations reduced by half.
The animals lashed ropes around the boulder, and then all the animals that could grab hold of the rope, even the pigs sometimes, pulled the boulder up the slope and to the top of the quarry, and toppled it over the edge to shatter to pieces below.
The new policy was that from now onwards Animal Farm would engage in trade with the neighboring farms: not, of course, for any commercial purpose, but simply in order to obtain certain materials which were urgently necessary. The needs of the Windmill must override everything else.
What commandment did the pigs break? How did they cover it up?
The pigs broke the fourth commandment that said, "No animal shall sleep in a bed". They covered it up by adding the words "with sheets". So the commandment became, "No animal shall sleep in a bed with sheets".
Why did Napoleon decide to participate in trade? What will he trade?
To obtain certain materials which were urgently necessary. The needs of the windmill must override everything else. He will trade stacks of hay and part of the current year's wheat crop and later on if more money were needed it would have to be made up by the sale of eggs.
He is a sly-looking little man with side whiskers, a solicitor in a very small way of business. His job was act as an intermediary between Animal farm and the outside world.