As a preface I'm using ViEmu although I dont think this affects anything. I would simply like to scroll up in the Text Editor along with moving the cursor to the relative screen position.
As an example, if my text editor displays 100 lines of viewable code (1 - 100) and my cursor is on line 20, when I scroll down to the next viewable 100 lines (101 -200) I would like the cursor to be at 120.
Using the VS command Edit.ScrollDown scrolls the code down as expected but leaving the cursor at line 20 instead of moving it to 120. Is there another command to use or any way to alter this behavior?
As noted in the question you seem to be wanting to re-map Page Down to another key (due to limited keyboard).
To identify which command a key is mapped to open the keyboard customisation dialogue and type in the current key into the short key text box and then look at what it is currently mapped to.
Unfortunately this doesn't work for page down (control-page down does work, but that doesn't help here).
Entering "page" into the command filter does: Edit.PageDown is mapped to Page Down in the text editor. Map this command to another shortcut.