Keeps 5 days refrigerated and freezes 3 months — freeze it without the pasta. It thickens considerably as it sits; loosen with broth or water when reheating.
As written here, yes. Traditionally it varies by region and often includes pancetta or a ham bone, so it isn't inherently vegetarian.
Under-seasoned and under-acidic. Salt properly, then finish with a splash of red wine vinegar or lemon — beans and vegetables need acid to lift them.
Yes. Soak overnight and simmer them separately until tender before adding, or they'll never soften in an acidic tomato broth.