Yeah, I see your point on the chair rotation. I was thinking the windows top and bottom were similar to the small windows below the instrument cluster on a helicopter, to assist with visual confirmation of altitude during landings. Would it be worth it to program in a multi-position lock switch on the seat rotation? One for interlock so that the seat is in line with the normal, "up" position for landing, then one for free rotation, and maybe 1 or more settings for various locked limits? Just a suggestion.
On the size of the y-unit, what does that value represent? is that a cross section of sorts, because with both the lander and ranger, the "horizontal" plane of the vessel is quite large, especially in relation to the other two planes.
Edit: On the issue of windows, increased visibility is always a desirable trait in any vessel, given that structural strength and crew safety aren't compromised.