It should be Hutsi! I remember this subject from a while back
A small portion of the virus itself mixed with the componentes of the vaccine
The researchers kept their identities secret because, if they had revealed that their purpouse was to conduct an experiment on the behaviours of the people in the bar, it might have triggered that some people changed their usual attitudes because they know that their 'figures' will be kept in a record.
Maybe some people will drink less as they feel embarrased if some other person is testing how many beers they end. Others, might want to prove themselves 'strong' and drink much more than usual. People change their behaviour sometimes when they are aware that they are watched. This is called the observer effect.
He would be squeezing lemons to get lemonade and to sell it....Obvious
The Union was more industrialized, and had a larger number of troops
The Confederacy was making a defence on home ground, and had experienced military officers.
A fun fact is that before the war happened General Robert E. Lee was actually asked to be a Officer for the Union but when his home state resided from the union he decided to become and officer for the Confederacy. The reason behind his decision is because he didn't want to be fighting against his home state.
Hope this helped