You can fit a few maps internally, but you're right about a card being a good idea. You want a microSD card, probably 4GB size, Class 6.
It's a Garmin application. If your unit came with BaseCamp, consider getting the Mapsource application as well for this purpose, available here:
http://www8.garmin.c...ails.jsp?id=209
No.
You select the map offered to you from gpsfiledepot.com, then you may select smaller portions to send to your Dakota using Mapsource.
Might be, if most of us hadn't gone right up the same path with the same questions!
Thanks!