The 150mm on 4x5 is a "normal" lens so, yes, a bit wide perhaps for portraiture, but quite usable as such. I like a 200mm lens on 4x5 for portrait work. As for minimum focus distance, you can get pretty close. Rather than using the RF, try focusing using the ground glass. To get enough bellows extension, you might need to fold down the infinity stops and pull the front standard out farther.

Dan