Customary to give condolence/congrats $

Is my company (a 50 person Tokyo-based branch of a US company) expected to give $ to an employee upon birth of a child/death of a family member? How much is common? Are flowers acceptable (seems that they are as long as I inform family?) Do companies typically have a written policy on this?

Yes, Japanese companies typically have a written policy on employees' families' birth and death etc. You should refer to it if you are going to do something on behalf of your company. If you are doing something as a colleague or friend that's another story, of course.

Oh, you are a Tokyo-based branch of a US company and not a US-based branch of a Tokyo company. I'm sorry, I misread it. But still, wouldn't it be safe to ask your head office if you can't look it up yourself?