Verizon Wireless smartphones--Made w/no Wifi or just deactivated in their units?

I am a Verizon cellphone customer but want a smartphone that can also access the internet through by wifi. Questions:

--Can anyone tell me if their smartphones aren't manufactured with wifi or if it is just turned off?

--If their wifi is just turned off, is there a way to turn it back on?

--If they don't have wifi manufactured in, is there some sort of wireless adapter for Verizon smartphones that will get me on wifi at hotspots?

Thanks for your help!