RE: How does changing the prop length/pitch affect performance?
As with many things in life --- it depends. Prop related performance is an interactive process -- it is not always a clearly predictable case. The engine's performance is affected by the prop selected --- but the prop's performance is affected by the engine's performance characteristics, the airframe in use & by its own particular design characteristics.
In general (and working within the engine's accepted performance envelope) a steeper pitch means slower acceleration & climb, but (sometimes) greater top speed. An increase in diameter improves prop efficiency (usually) & increases total thrust (usually), giving faster acceleration, less loss of speed in turns, better climb & (sometimes) lower top speed.
In the relationship between pitch and diameter, an increase in diameter raises the power load (required power that the engine must produce), faster than an increase in pitch does. A 10-6, for example, is roughly equivalent to an 11-4 in power load, assuming both props are of the same design & made from the same material. However, the performance that the airframe derives from those two props can be very different & it is highly dependent upon the airframe itself. A light, clean, low drag airframe will go faster with the 10-6 than it would with the 11-4, but a large, draggy. &/or heavy airframe may very well go faster with the 11-4. In either case, the 11-4 will give better climb.
In the examples that you gave (10-6, 10-7, 11-5 & 11-6), you must also consider the power plant -- only the 10-6 is suited to your engine and airframe combo. The LA .40 can't effectively pull any of those other props, particularly the 11-6. It will spin the 10-6 (or 11-4) at ~ 12,000 - 12, 100 rpm (close to the torque peak at 12,700), but the revs will fall below 11,000 (say 10,800 - 10,900) with the 10-7 & ~ 10,400 with the 11-6 -- well below both the power & torque peaks.
After all of that -- keep the 10-6, or alternatively, use an 11-4.
BTW, a spinner will improve prop performance, but keep the spinner diameter within 25% of the prop diameter.