Re: Color grading
The entire image is quite warm. It has heavy shadows. You can process out just as you normally would. To get the overall you will probably end up using curves to pull the shadows down a bit overall as well as the same kind of adjustment in the blue channel to get those yellowish tones. Adjust the green channel as necessary to balance things. You may need to fine tune clothing or skintones a bit.
Note that they darkened the corners quite a bit to emphasize the "vintage" feeling of the overall image. It's certainly meant to have somewhat of a vintage feel, although it's a bit mixed in that regard. I think the styling on the boy feels like it pulls more from the 1950s. His hair styling is definitely influenced by that.
Beyond the overall grading, remember that nailing the lighting helps, you may need to fine tune the details no matter what. Eyes, lips, cheeks, and clothing are very prominent aspects of this image.