I've shut my data plan while I am outside Canada, but strangely, I see the rooming symbol in my S4. In the past, rooming normally won't show up after I turn the data plan off, no matter where I was outside Canada. Will I get charge when I use wifi?
You will not get charged for using wifi while roaming. You will be charged for using the phone for calling/answering calls or sending/receiving texts. You turned off data roaming. This is not the same as turning off the ability to roam.