I have a friend that works there as an engineer and as far as he has told me they pay about average to a bit below average and the engineers sit in an open plan office.

Just checked glassdoor, and a senior software engineer makes ~114k so that gives you a pretty good idea of their compensation structure...average.

Not to call you a liar or anything, but I get emails from wayfair recruiters all the time and my understanding of their compensation has led me not to respond but I'd love to be wrong.