Are hernias usually very painful?

Maybe. Hernias manifest with a variety of symptoms, pain being among them. It is highly variable how patients respond to a hernia, but pain and sidcomfort, along with an enlarging bulge under the skin are common. There are many however that have hernias of all sizes with no symptoms at all. Hope this helps!
No. Most hernias cause only a dull ache, typically worsened by lifting or prolonged activity. The most telltale sign of a hernia is a bulge; if the bulge becomes acutely tender and cannot be reduced, this may be a sign of a surgical emergency, and requires immediate medical attention.