Can you choose where to insert your new slide in power point in the new slide list arrow?

You can drop and drag slides wherever you would like to adjust their order, when in the slide sorter view. You can do the same thing in the default view - when you have the slide tiles to the left and the slide you're working is taking up most of the screen (can't think of that views name off the top of my head, but it's the default).

Just click on the tile (smaller slide to the left hand side of the screen) and drag it (inside the tiles) to where you'd like it to land. That process needs to be done while staying in the tiles, all in the view pane to the left hand side of your screen.

This website should allow for screenshots.