1.MAX to make this rule model, of course, press and hold 3 with POLY modeling method, and try to keep squeezing out the edges.
2。 In general, Boolean operations are not used for modeling.
3。 Chairs and sofas are independent, including instruments. After your big model is built, you can do it slowly later. Just come out independently and put it in.
As for your modifier, it may be because your face has four more points. . Four points or three points can make a face, but in fact, four points can make two faces, and five points can't make faces. You need to give this model a double-sided material. Sometimes you can't see the model because the normal of the face is inside.
Sometimes it is a little difficult for MAX to weld. There seems to be a reason to forget. Anyway, it probably has something to do with the surface.
Usually, the smooth mesh modifier is smooth.