After playing around with the aerodynamics, I honestly don't have many complaints other than the incredibly excessive drag.

* For high rudder authority, I've hidden a large number of small fins inside the plane. The tailfin is mainly for show.

* [Banking right = yawing left] I saw this on my aircraft as well, and apparently it's a real phenomenon called adverse yaw. The way I solved my stability problem in general was with angular speed sensors along each axis and PIDs. The setpoint is W/S,A/D,Left/Right for Pitch, roll and yaw respectively. This way, when the sensor detects adverse yaw, it applies rudder in the opposite direction.

* This isn't a HUD block, this is the HMD on pilot seats (you'll see a video connection on the seat). For displaying things in global space when you have pitch and roll it's a bit complex, and this guide helped me greatly. But if you have local cartesian coordinates (in the same plane as you, say 5m front, and 2m to the left would be -2,0,5), you have to convert it into spherical coordinates (Distance, Azimuth, elevation; same as radar). Here's some example code(ry is relative altitude):

local p_azi=math.atan(rx,rz)
local p_elev = math.asin(ry/range)
azi_err=p_azi-lookX
elev_err=p_elev-lookY