Propellers add quite a bit of drag when facing the front, but you can eliminate all that while keeping the thrust by just putting it at the tail and then inverting it.

The starter cockpit costs twice as much as the normal fuselage, weighs 50% more, adds a bit of drag, while all having the same cargo space. So yea, it's completely useless besides looking cool.
But as you earn more money and scraps, definitely switch to using the upgraded cockpits, as the more advanced ones offer some insane weight to cargo ratio.

Hear me out, there are basically four ways to increase cargo capacity in the game:
1) make the fuselage longer (plane harder to maneuver)
2) make the fuselage wider (increases air resistance)
3) make the fuselage more angular (no effect besides making the plane look like a fridge)
4) stack multiple fuselages together using the positioning tool (feels like cheating and too expensive for early game)

So for early game, the most economical and efficient way to increase storage is to turn the plane into a flying fridge, and then stack more fuselage inside it once there's more money so the plane size stays managable.

Now you can easily carry most of the early game cargo in bulk!

This removes a lot of unnecessary drag, and can be easily done with the positioning tool.

Since the fuselage is not affected by grinding against the ground, the whole point of wheels is basically to position the plane at an angle that makes taking off easier, so all you need are a pair of front wheels adjusted to the right height using the positioning tool.
Not having a vertical stabilizer also doesn't affect plane control at all, not even the yaw. It's much better to invest the money on windbrakes and drag chutes to save you from crash landings instead!