Clark is human Lois is kryptonian has been done and quite well as linked above. Having Lois have as a sister Kara Zor-El (Supergirl) would be interesting. Having her recognize that Clark is kryptonian before he appears as Superman because he does some of the same things to hide his powers as her sister does would be amusing. Giving her the name Linda even fits.
I can see Sam being interested in learning what the limits of her powers are and doing experiments but he isn't a evil person. So the relationship between her and Sam would be about the same as Lois's is I'd expect.
