Regarding load ratings, you just want to make sure the tire's rating is high enough for the car you're putting it on.
I've used many XL rated tires on my MS3.
http://blog.tirerack.com/blog/miles-of-smiles/xl-vs-standard-load-tires-what-should-i-do
Yeah that's another thing that sucks about the stock pads. There is no need for them to produce that much dust relative to their stopping power... Only pads I've ever used on this car that dusted more were track-only pads.
Stoptech Street Performance pads (from what I remember) were very similar to the OEM pads in bite and modulation and cost $80. I even tracked the car on them once (on sticky street tires) and they held up reasonably well for a street pad (though I wouldn't buy them specifically with tracking in...