Speaking of the height/width wording, I was wondering if it would be possible to make it so that one could chose whether the file panel/directory tree was horizontally split or vertically split?
There is such an option. You had to use it as by default vertical splitting is used (hence the wording) but you are using horizontal splitting.
The option is Show directory tree left of file list:
https://winscp.net/eng/docs/ui_pref_commander
I find that a horizontal split shows more columns in the file panel on the monitors I use without needing to use the scrollbars.
But you use horizontal splitting, right?