Strictly speaking, any 3d figure with anything besides 6 sides cannot consist of rectangles. However, the name for an 8-sided figure is "octahedron".
YES
A cuboid.
Cuboid.
Yes, if it is bound by plane figures, just add the area of each plane figure. If it has a curved surface, divide it into many small pieces, to approximate the area with small rectangles or triangles, then add them up.
pentagonal prism
Strictly speaking, any 3d figure with anything besides 6 sides cannot consist of rectangles. However, the name for an 8-sided figure is "octahedron".
YES
A cuboid.
Cuboid.
A butt
Cuboid
cube
Yes, if it is bound by plane figures, just add the area of each plane figure. If it has a curved surface, divide it into many small pieces, to approximate the area with small rectangles or triangles, then add them up.
A triangular pyramid.
a hexagonal prism
Squares, rectangles, and the rhombus.