I think you understood right. By skinning I meant weighting a polygon mesh to a skeleton for the purposes of posing/animation. By using cards for feathers, I meant using the same technique as for polygon hair.
If your goal is video game, then it will have to be a polygon anyway, so you'll have to convert it. If you're transferring a nurbs' details to a polygon that could work but you'd have to still create a polygonal low poly. Correct me if I'm wrong on any of this?
In the Unwrap editor, choose Polygon subobject, then in the Select menu choose “Select Overlapped Polygons”. More info: https://help.autodesk.com/view/3DSMAX/2024/ENU/?guid=GUID-2AEF6A44-859D-434E-8E08-00D2A480A0CD
Mesh works with triangles. A triangle is a 3 sided polygon. Poly works with polygons, with any number of sides. Internally, each polygon is still made from triangles, but the trianglesness is hidden from the user. Instead of seeng a square as 2 triangles, they see it as a square.