Conocerás a tu hijo cuando tengas que conocerlo..

Conocerás a tu hijo cuando tengas que conocerlo..
 

This appears in the song Corre by Jesse y Joy at the end, I had some questions about it...

Ref:

Conoceras a tu hijo cuando tengas que conocerlo...

I understood it as "you will know your son when you may have to know him..."

is this correct?

Question #2: What is the exact translation of "me da igual"? Is it "I couldn't care less" ? How is it different from "que más da"? Are they equivalent?

You're close.
"You'll know your son when you have to meet/know him..."

Me da igual = It's all the same to me / Whatever / I don't care
"¿Qué más da?" basically means the same thing. Who cares? I don't care.

Thanks for posting that video! That was a clearly sung song that was easy to understand and I actually enjoyed that style as well. Muchas gracias