You can spawn a triangle, but avoid using other behaviors like Pin with physics objects. Also, avoid using non-physics actions like directly changing object angle or position. See the manual for more info.
I don't know how to apply a force in the direction of movement and then rotate the triangle with forces.
You can use "Apply force at angle" to propel forward.
There are several ways to rotate, you can apply angular velocity or torque, or apply force to different points of the object.