The Shield Ship was part of the Galactic Civil War and the Grand Admiral Thrawn saga. I think it was a comic series, and a really good one. Jorus Caboath was one of my favorite characters from the expanded lore, and, of course, the Noghri death commandos were a ton of awesome.
It is an Interceptor. The Advanced is thicker.
The shield ship is meant to protect ships traveling near stars, they stay in the dark behind the large disc.
The T-47 Airspeeder was never meant for snow. It is not a snowspeeder. It was for towing cargo, hence the tow cable.
They specifically tell Han that they're having a lot of trouble adapting the speeders to work in the snow when he's looking for Luke in Empire at Echo Base on Hoth.