When the belt is tight, it makes the upper and lower discs act as one componant. Engine rotation is then delivered to the lower disc and the blade spins.

Husky does make a tool for it, I made my own years before they made one available. An old socket sized about the same as the outer diameter of the three spokes can be notched out to do the job. With the side cover chucked up in a vice, the modified socket in the wratchet or breaker bar makes quick work of returning the mechanism. I see 3 or 4 of these a month from folks who pryed the cover off with the brake set or who were messing with the brake to see how they work. Curriosity can be a good thing but sometimes it bites.

Rotor spec for your car is 1.102 nominal, 1.024 minimum thickness. That means when machining my preference is to not go closer than .030 of the discard or 1.054 for the unofficial minimum machining thickness. Rotors of course can be machined off the car and have been for decades. However the preferred method for your car is to machine them on the car. That provides automatic correction for any wheel hub run-out. That's one of the reasons they are fastened to the hub with those two screws. The other reason of course is so that during initial assembly they don't fall off on the assembly line before the calipers are installed. But when you need to remove them, how does a tech do it? I have two methods. One is an impact screwdriver that operates by inertia. There are spiral groves in between the inner and outer portions of the tool, and when you hit it with a hammer and force it to collapse, the inertia of the outer half not wanting to start turning, forces the inner section to try t turn and tighten or loosen a screw depending on the tools setting. Almost every motorcyle tech will be familliar with this tool, they have existed since the 60's at the least. In fact mine is probably the oldest tool in my tool box, having purchased it in the early 70's. But it does not always work, sometimes the screws are simply too tight, and I break the screwdriver bit pretty often. That forces me to use the second method, which ruins the screw. I take a large center punch, and start by making a deep pin hole into the edge of the screw, without hitting the rotor. Once the hole is there, I move the punch to an angle to force the screw to turn by driving it with the punch and hammer. With practice this is really simple and has never failed to remove one of those screws. On a few occasions I have even been able to re-use them. Lastly, 1 1/16" translates to approximately 1.060 (about .030 for 1/32) IMO you would not have been able to machine those rotors successfully, as they would be getting too thin to allow for enough material to deal with the heat generated by braking. Plus six years old on a vented rotor, the rust that builds up in the middle cooling vanes prevents the rotor from cooling efficiently. Plus, the same rusting makes the rotor structurally weaker and prone to "crushing" which is one of the primary causes of rotor thickness variation. All those things together make it unadviseable to have not replaced these rotors when doing the brakes. At the same time we haven't talked about how good the calipers really are, and the caliper slides, how free are they? What about the rear brakes, did you check them? The parking brake assembly? How is the fluid, should it have been flushed? There is so much more to replacing brakes, than just simply slamming a set of pads. That's why you will never see my quote things like the "$99.00 brakes, additional work extra routine".

4 wheel disc brakes offer a number of advantages, the first of which is maintaining brake balance under different situations such as normal, and very heavy brake use. Disc brakes also lend themselves to being more effective with ABS systems, and lastly have the advantage of reducing unsprung weight. As far as AWD vs 2WD, the main difference would of course be drag. Try pushing an AWD car around a parking lot, and then do the same with a similar sized 2WD. For the most part you will notice a slight difference in a straight line, but turn the wheels and you might notice you can no longer push the car because of the extra drag in the AWD/4WD. As far as directing "more" power to the wheel that spins, lets just leave it at the idea that it's not as intelligent of a system directing power as the advertising might make you think. When one wheel loses traction, the other has no choice but to push the car harder because the torque being applied to both the wheels is the same. So it's not that one gets increased torque, its simply better envisioned as the other slipping wheel not helping. BTW for testing purposes (and some other uses) there is typically a fuse holder under-hood on the Subaru to disengage the AWD, and make it just a FWD car. However extended use of this option has been shown to overheat the solenoid that controls that function and once damaged you now have no AWD. To shut off the AWD, you install a fuse into the holder. Removing the fuse allows the AWD to function again.