Looking to hook up this unit to power just so I can play with it and get used to some of the controls before I take it out on the water in a couple weeks. 

Absolutely. I know some guys that even have mounts in their trucks and use the units for navigation on the way to the lake  No different than the big store displays 

 I don’t know what brand you have but you should have a demo mode.  The Huminbird demo mode gives you recorded data so you can learn all the functions and see maps and sonar readings while you learn the controls. 

Yes. I do it all the time in the winter to update graphs in my house.