More or less. "Ты где" has a more emotional impact and I'd rather use it when calling a person by name or asking where the heck the person is. They are both valid, though, "Где ты?" being a more generic form.
Thank you for answering all of our questions and of course for making this amazing course!!
I spent a lot of time looking for the question mark in my latin keyboard running Russian mode. Lol. I found it on SHIFT+7, hahaha
It is singular "you" used with people you know. The one that was "thou" in English about 500 years ago (not in much use these days).
We typically switch to the plural/polite "you"(вы) with strangers and superiours. Ты is used inside one's family and also with kids regardless of your age and whether you know them or not.