Can diet affect angina?

To a degree. Angina is a manifestation of coronary artery disease whose primary cause is the formation of cholesterol plaques that narrow the vessel. Cholesterol plaque formation is directly linked to the degree of cholesterol concentration which, in turn, is partly dependent on the exogenous cholesterol supply. So, foods high in cholesterol will contribute to plaque formation and eventually to angina.
Yes. Overeating redirects blood flow and is more work for the heart as well as caffeine which can raise BP and heart rate and precipitate an anginal attack.