I was in touch with Evesham about a year ago although it related to an TFT screen rather than a laptop. I was told at the time, as far as I remember, that typically 4 dead pixels were considered acceptable. Unless it specifically stated that it would be perfect then you have to accept it. Like you I thought they either worked or didn't but it may be that only one of the colours is affected so it depends on the background.
All the laptops I've owned or used over the last few years have been warm to very warm after they've been in use for a time.
Don't know about the WLAN thing though.