Excellent Excel questions about rows and clipboard

I'm working a lot with Excel in my work, but I still have problems with some pretty basic things (IMHO).
An example: I have two large spreadsheets and I want to copy and paste, say 100 rows of the second one somewhere IN THE MIDDLE of the first. It seems I can not understand how to do it so that those rows stick together and everything that is already there moves down. The spreadsheet has many columns and I want all the cells to move down and not just those in column A.
What happens is that I do not want to copy and paste entire rows, because there are formulas that are broken (start referring to the source XLSX file), so I try to copy and paste only the first column.

If I copy this single column (1: 100), right-click on the number in the row in the destination worksheet and choose "insert copied cells", multiply this column in all the remaining columns to the extreme further away from the area of ​​the spreadsheet, which is ridiculous and it's not what I obviously want.

If I copy and I have only one selected cell while I paste it, it asks me if I want to move the cells to the right or to the bottom. If I choose below, only the first column moves, but the rest of the columns remain, which is also incorrect.
So tell me how you would do it? I really do not want to have to count the number of rows I'm pasting and then right click / insert so many times to make room for what I want to paste there.

Follow-up question: if I would really like to insert a hundred empty rows in the middle of my spreadsheet, how do I do it? I did not find any menu for this.