Bali belly is a 'thing''. Though to be more accurate it's more of a travellers' tummy thing and common in many tropical places. It can be to do with our immune systems not being used to the impact of the local sanitation. Taking probiotics before you go and during your trip can really help settle your stomach.
These apps are like Uber. And there's only 2 ways to travel in Bali - on a grab bike or a car. Public transport is few and far between. Downloading these apps will make it getting about easier.