Yes. Full activity, unless specifically restricted by your own surgeon, is expected as soon as the patient is capable of performing these exercises and cleared by the surgeon to do so. Typically, stomach crunches are allowed 4-6 weeks postop. Some more conservative surgeons prefer to wait 2-3 months, but typically, the healing process permits for strenuous activity as soon as 2 weeks.
Usually 3-6 weeks. Inguinal hernia repair is associated with significant discomfort for the first few weeks after surgery that precludes these exercises. My recommendation is dependent on my method of repair, their health, and their goals (if their goal is weight loss, aerobic exercise is much more important). A common error is to assume these exercises reduce the risk of another hernia-it may do the opposite!