Four Questions on the Fathers of the Presidents

Forty-three different men have been President of the United States.  Only seven of their fathers were alive when they took office.  Of these seven fathers, two had themselves been President.  One of the remaining five fathers had the privilege of swearing in his own son.

Not all seven fathers were able to attend their sons’ inaugurations, but one father was able to attend twice,… and he was able to bring his wife, the mother of the President, both times.

So, who were these fathers?

1. Who were the two fathers who had themselves been President?

2. Who was the father who got to swear in his own son?

3. Who was the father who was able to bring his wife to two inaugurals of their son?

4. Finally, who were all seven fathers?