4)

raz = Plot3D[x^2 - y^2, {x, -3, 3}, {y, -3, 3}, BoundaryStyle -> None,
    BoxRatios -> {1, 1, 2}, PlotStyle -> Orange,
   ViewCenter -> Automatic, ViewVector -> Automatic];

dva = ContourPlot3D[x, {x, -100, 100}, {y, -100, 100}, {z, -100, 100},
    Contours -> {-2, 0, 2}, ContourStyle -> {Opacity[0.6]},
   PlotPoints -> 50, Mesh -> {{0}}, BoxRatios -> {1, 1, 1}];

Show[{raz, dva}, Boxed -> False]


raz = Plot3D[x^2 + y^2, {x, -3, 3}, {y, -3, 3}, BoundaryStyle -> None,
    BoxRatios -> {1, 1, 2}, PlotStyle -> Orange,
   ViewCenter -> Automatic, ViewVector -> Automatic];

dva = ContourPlot3D[x, {x, -100, 100}, {y, -100, 100}, {z, -100, 100},
    Contours -> {-2, 0, 2}, ContourStyle -> {Opacity[0.6]},
   PlotPoints -> 50, Mesh -> {{0}}, BoxRatios -> {1, 1, 1}];

Show[{raz, dva}, Boxed -> False]