Battery life may vary based on the version of firmware used in a receiver so not all units with the same model name have equal battery life. All navigation information, plots, maps etc. are displayed on screens of varying size and quality. Newer receivers have much improved screen resolution, some with colour, and most offer backlighting for use in the dark as well as screen contrast adjustment to optimize viewing. Water and weather resiliency is evidently important in an outdoor environment. Even though receivers may be advertised as waterproof or water resistant I would suggest acquiring a waterproof case designed specifically for GPS receivers.
Several models accommodating different receiver sizes and antenna types are available.
Once selected, these can be downloaded directly into compatible GPS receivers and, along with the base map, printed for use during the trip. However Canadian and international digital maps are rapidly being produced. For those areas without digital map coverage, some programs allow maps to be scanned and subsequently used as above. Follow initialization instructions carefully. The GPS satellite constellation varies with time so it is important for the receiver to have the latest satellite almanacs.