For the image overlap, can you inspect the docking for your image? Is there any negative values?
It could alos be possible due to your section having a fixed px height and your other element may be doing beyond that value.
The best way to work with Grid is to use the Grid Area in inspect window. Make sure your element has the right column start/end row start/end. Once you have it in the right grid , then expand it and will fit within the expected grid.