you can do with with bootstrap classes.
Also you can do it with layout-grid widget.
yes possible; not sure if you want to place a row inside another row or a row above another row. both are possible, see image
This is how is made and this is what I'm looking for
Seems you try to achieve something with containers, while you could use a layout grid instead.
The layout grid is the Mendix widget to model a bootstrap grid.
When adding the layout grid you can select a predefined setup, but you can easily change that after placing, by adding rows, columns as you wish. In the general section you can either set the column width to auto-fill (every column will size equally) or manual, where you can specify a fixed distribution.