Crap. Finally one I could have answered all parts and I'm too late.
I just finished reading a book on the very subject with all of the characters including Dr. Willard Bliss. Garfield suffered for 2 months after the shooting. The bullet itself wasn't life threatening, but Garfield eventually succumbed to infection from the doctors' (there were many who examined him) fingers probing the bullet hole.
Bliss had taken charge (for no apparent reason other than ego) and Garfield's death was a blow to his practice. Bliss denied any infection even though Garfield fielded all of the symptoms. The infection was discovered spread throughout Garfield's body when the autopsy was done.
Guiteau was a lunatic thought he would be praised as a hero for killing Garfield. Almost the whole time he was in prison, he expected A) the U.S. Army to come to his rescue or B) figured Chester A. Arthur would grant him a full pardon.
You could almost write a book on Guiteau's experiences.