
WiFi usually bounces inside the home as it is broadcast in the home. Won't affect the coverage inside the home. Outside the home, depends on where the broadcast point it.
Cell reception will go down if you aren't near a window. There are booster that you can get for the signal if it is problematic.
My wife and I are getting a metal roof put in in the near future. We have concerns regarding the affects the roof may have on our cell and WiFi reception. Any words of advice to put our minds at ease?