Fish don't really get impaction. Keep in mind that they are sand-sifters by nature--it would be pretty silly if their method of getting food somehow led to their deaths! As they take in and scatter the sand, they are capable of filtering it out through their gills. Reptiles don't have this advantage. :)
The only sand I've used is Seachem's Flourite black sand: http://www.fosterandsmithaquatics.co...70&pcatid=4870
my kuhli loaches really like it, and it's enriched for live plants. The black color really makes the fish stand out. It also isn't super duper fine like some sands, making it easier to clean.
Be aware that you will have to thoroughly rinse your sand, no matter which type you pick. There is often quite a bit of silt mixed in with it. The more thoroughly you rinse, the clearer your water will be. I put the sand in a bucket outside and fill it with a garden hose--stir the sand while letting the bucket overflow. The silt will flow out of the bucked with the overflow, and the heavier sand will stay put in the bottom.
As for cleaning the sand, it won't necessarily be easier because of the cories. Cories do help with debris, but all they do is turn it into poop. It's not like the crap on the bottom of your tank is just magically going to be gone. :) This is why I prefer black sand--with white or light colored sand you see every single turd. >___> Just not pleasant! To clean, instead of digging your gravel vac into the substrate like you would if you had gravel, you just sweep across the sand without really touching it. Just close enough for the suction to stir up the sand and release the particles into the siphon. Once you get the hang of it, it's quite easy.