So if I order from amazon, I'll receive a sd card with the map?
You'll receive a micro SD card already inserted into an sd card adapter.
What about future updates, does it mean I'll have to buy again?
You
don't get future updates with the sd card version; if you want updates then you'll have to get the CD version which provides you the capability to update online. I'm not sure if you get free future updates beyond the first update.
You may be able to get the CD version in downloadable format (please check Garmin web site for that option)