I suspect HWD is muddying the waters rather than clearing them.
A sideslip is a sideslip however you refer to it. Rudder is applied to yaw the fuselage to one side and aileron is applied to keep the wings level. Some elevator input is normally also required to stop the nose from dropping.
In the one-wing low landing scenarion the approach path is aligned with the runway centreline. The drift that would normally be caused by the wind is offset by banking the aircraft towards the wind direction, producing a horizontal component into wind and the resulting turning effect is cancelled by applying opposite rudder. It's still a sideslip but carried out without the wings level.
As far as roll effect goes the vertical position of the centre of lateral resistance in relation to the centre of lift will have some effect (it's above on a high wing and below on a low-wing, somewhere in the middle on a biplane).
There will be a spanwise element in the flow across the wing, effectively an increase in chord. While the wing in the lee of the fuselage will lose some airflow at the root the same will happen on the other wing as spanwise flow hits the fuselage causing a pressure build up that will disrupt the flow further out.
I find it's best not to ponder these things too much, just go out and practice at a safe height until it comes naturally.
The compniation of no flaps on the Luscombe, high trees on the approach and the downslope on 03 at Popham makes it an ideal place to refine the technique.
Mike