It occurs to me, if one is trying to copy something then you might need craftsmanship or maybe alertness, however most of the time one is creating something original. So what happens if you get a good roll then? Are you an aesthetically pleasing lamp? What happens on a low roll? Ugly lamp? Most people aren't going to question an object even if it is an ugly lamp, or really oddly shaped rock, so what is the value in the roll? My gut is that most of the time you should be using deceit or stealth as they actually make sense regardless of form (I.E. the ability to convincingly be an object, or the ability to be less obvious), and if you really go by RAW then if one does not use deceit or stealth then one does not receive the +4 bonus (the power says +4 to deceit or stealth), but that's just being nit-picky.
As far as the second question, my read on it is that you actually are that form (as opposed to just looking like it) and a lamp is capable of being plugged into a wall socket and producing light with electricity. We have no idea what that might feel like, maybe it's uncomfortable, but it's just as likely that it feels pleasant or even completely the same as not conducting electricity. Now that I'm thinking about it, I imagine that a craftsmanship roll may effect whether one conducts electricity in the proper manner to create light or not.