ipad and gps help

Hi, I need some help. We're going to buy an ipad (or ipad mini or some other tablet) for our next trip to Europe. Mainly for the internet, and as an e-reader, but also as a GPS, for driving, and hiking, and walking anywhere it feels safe to have the device out and in our hands. I've never used GPS for driving or hiking (although I have basic familiarity with GPS concepts from work, years ago, in the forestry field, collecting and processing locational data with early generation recievers). So doing research it looks confusing and difficult. I see with the ipad or mini, only the units with cell capability have a gps receiver. But I won't have a cell subscription because I won't want in incur high roaming costs. But it might be cheaper to buy a separate gps receiver to pair with a wifi only ipad. But what receiver is compatible? And what apps will work? And what about off-line maps? Maybe this is crazy, we've always survived with paper maps. Although they've always seemed inadequate. In Italy, two sets of maps, one with most of the roads, another with fewer roads but most of the road numbers - things like that. Can anyone help, thanks,
Jim