Are those Darters?

in the new Castle Map pack trailer, on the map outcast, you can see a small cargo ship in the map’s background, functioning kind of like the Hornet track model from Skyline
it looks a lot like the D82-EST “darter” from Halo wars

(it’s shown at 0:08 in the trailer)

Looks like it!

they upgraded the supply pad

They are indeed, it was confirmed in the galleries.

Supply pad, upgraded!