The pulleys do swap, take it from someone who worked in an automotive electrical shop.
As for lining up with the stock bracket there are different clocks that can be used to move the mounts around. You simply disconnect the 4 bolts that hold the case together and rotate the case to get the mounts where you need them. I know that when I put my serp setup in, I am mounting a CS144 into the spot that is currently occupied by the CS130 my old Astro used. According to my buddy, that used to run the shop and has been doing this stuff for over 25 years, the CS144 will be bigger and will require me to find a belt that will work, but it will mount right into the bracket the CS130 was in. And for reference, the bracket you have there appears identical to the ones I took off the 4.3 to use for my Blazer so it should have had a CS130 in it originally.
Dremu's posts about the rest are very good, and will give you a good reference. A simple way to avoid the resistor is just to setup a light on the dash. That's my plan anyway, a second warning system can't hurt since the gauges are not always easy to see.
