Many intermediates in glycolysis and citric acid cycle use ATP, so only about 26 ATP are available afterwards
They are in the matrix, so need to be moved out
Voltage difference across membrane. ATP is slightly negative than ADP, so inside is negative and outside is positive, so the ATP wants to go to the outside. Through an ATP/ADP antiporter, so ADP is provided for ATP synthase
Phosphate transporter takes advantage of pH gradient. Inner is more basic than intermembrane space.