You can download a save data to an SD card and transfer it to the SD on the adapter, but I don't know if you can directly download the data and expect it to work.
You can see if it has Priiloader by turning on the wii and inmediately pressing and holding the reset button.
I'd say that you have a Banner Brick, so you can search for corrupted channels or wads on your wii to eliminate them.
Reply if you have any more problems!
I was thinking of making a Double Dash banner, but the thing I have in mind is totally different from this. I'll try and make it so you can see what i'm talking about