Is it possible for cauda equina to present without extreme pain? where would pain be? is there a complete loss of bladder function?

Yes: Cauda equina syndrome may present without much pain especially if there is more effect on lower sacral nerve roots than low lumbar or upper sacral.

Not likely: There is a difference between cauda equina syndrome and conus medullaris syndrome. I have not seen painless cauda equina. Every patient I have seen is in excruciating, going to die, kind of pain. On the contrary, conus medullaris syndrome is often completely missed after thoracolumbar injury. Numbness of the saddle area of the groin with bowel & bladder dysfunction are present with hyper-reflexia.