I was told that unless the hernia is painful, you don't need to have it fixed. Mine doesn't hurt.
Diastasis recti is when your abdominal muscles get separated. Normally, the two bands run next to each other down your front, but with a diastasis, they get pushed apart and their is a gap between them. It weakens your abs and pelvic floor. When I try to reach something high or lift something heavy, it hurts like I have pulled something.
You have to do special exercises to fix it. Sit-ups won't help--they can actually make it worse.