Question

List all the different audiences you think Lincoln is addressing in his inaugural speech

Answer 1

The audience he was addressing to, was the union and basically the world. It was an oath he had to take as being the 16th president in the United States. 

Answer 2

In his inaugural speech, President Lincoln is primarily addressing American citizens, the people who make up the Union.
He specifically speaks to Southerners who have seceded from the Union and people in states that are planning to secede.
He may also be addressing the international community, particularly the country's allies, to reassure them.