So, I have these apps on my work iphone but have not signed up yet. I have a few newbie questions in relation to Uber and/or Grab.

This is a work phone so when I travel for leisure I don't get a data plan etc., I turn off my data and just use wifi, mostly just in the hotel checking emails and such.

If I am only on wifi can I still request an Uber or Grab car? I understand when I leave the hotel and I am somewhere else without wifi I will just have to hail a cab back.

For example we were just in Vegas and seen TONS of Uber/Grab cars picking up and dropping off people and it sounds it is much more reasonable. We are heading to Malaysia this winter and would like to use it there?

How does payment work. I understand you register your credit card and it is automatically charged. Do you know the price before ordering and if chosen can you also pay cash?

Any help would be appreciated!