Currency  
The Kuna and Lipa, with 100 Lipa to the Kuna. There are about 9.9 Kuna to the GB £
Cash machines are available in towns including Orebic. The bank is open from 8am till 2pm.
Some things are priced in Euros - restaurants, hotels for example. But you can always pay in Kuna.

Shops
Open early (about 7 am) usually shut for lunch then open till about 7pm. This varies out of season.

Links
Look at http://www.managedpropertysolutions.co.uk  and contact them if you want help with finding a house or apartment on the Peljesac Peninsula