Got the power cord in tonight, it will run the unit with no batteries, it uses the same cord as the Oregon. The power cord came from Garmin and is long and well built. Also tomorrow if I can get a chance, I'm going to experiment with the least solar capability. I have a 40 watt military cell and 4- 5 watt cells (20 Watts) and I will see what it takes to run it with no batteries in the unit. I am highly confident the 40 watt will be no problem, I'm just wondering how low of wattage will run it. As for micro SD cards, after experimenting more with it, here is what I can store in the battery compartment (water tight and secure).
The map experimental capabilities tested are as follows.
I can store 3 micro in the units battery compartment without interference. One card in the slot and 2 of them directly on top clears it from being pressed on by the batteries. What that means is I have 3 cards in the unit with these maps on board:

3- Micro SD cards total, all fits into the battery compartment.
(2- 4 gig SDHC Micro SD card and 1-2 gig Micro SD card)

Africa Street Map
Atlantic blue chart Portugal Azores
Australia Street Map
Borneo Street Map
Brazil Street Map
Canada Street Map
Caribbean Street Map
China Street Map
Europe Street Map
Indian Ocean
Japan Street Map
Malsing Street Map
Mexico Street Map
Middle East Street Map
New Zealand Street Map
Taiwan Street Map
Thailand Street Map
United States Street Map
24k Topographic US East, Central, West