I quite simple to add some one to a devWatch, you go onto their profile, and on the top right corner there'll be +watch or something like that, you just click on it.
Commenting, you just go to the space below the picture that you're able to put text into.
Btw, I knew it was you because you're real name is below your username, same with Brigittes(though I got the idea it was her when I noticed that my entire gallery had been faved by one person.
)