If a smartphone has no service, can you still use the WiFi? If you can will it still work?
Yes the WiFi will work. Also, you may be able to get a program which acts as a phone over the web. I of some PC ones, but not any for a smartphone.
Yes, but you can't use it for phone service, only data.
As stated above, the WiFi has nothing to do with your phone service, so yes, it will work.
Just to put my two cents in... Yes