The Wagner act is also known as the National Labor Standards act
C. Andrew Jackson, also if I'm correct, Martin Van Buren was also part of it.
They served with the Confederacy because they believed that the Confederacy fought the big central government that was being imposed by the Union and they wanted to fight this so as to keep sovereignty over their own land. They believed that the Union government didn't care about them while the Confederacy would give them room to breathe.
Because states might have an uneven amount of rebublican and democrat representatives. Say you have a state that has more democrats then republicans. The rebublicans end up getting screwed because they're is not enough of them.