Can I have both FGO NA version and FGO JP version in one device?

Yes you can have both on your phone. I tried to play on the Jp server as well but I quit not for long because I play for the story, 2nd only for the servants.

Yes, you can play both version on the same device.
No, it won't and each version is independent.

Can I get same data are my na FGO accomplished singularity on jp at some time on both versions