Yes and Yes.
A simple spin lock battery cover needs to be removed and then a battery/ calculator size battery is needed. I have not yet needed to replace mine after nearly 6 months of use.
The display can be tailored to however you want. My default front screen shows total distance, average speed, current speed, cadence and heart rate. For me they are the fields i need on my training rides.
Obviously if you require different fields then you can easily change them in the menu system.