question about commas please help

[Unregistered]

1) Oh god, it is really nice.

OR

2) Oh, god, it is really nice.

AND

3) Yeah baby, it is really nice.

OR

4) Yeah, baby, it is really nice.

 

[PlacidRan]

I'm writing a novel and need help. Do I require a comma after oh? Like: Oh, god, yes, it is really nice. Or should it be: Oh god, yes, it is really nice.

Also, which one is accurate: Yeah, baby, it is really nice. Or this one: Yeah baby, it is really nice.

Is "yeah baby" a conjecture? If it is, then it wouldn't need a comma.