I vacuumed the day before the shrimp arrived and did a 100% WC with Prime after I did. I don't normally vacuum any tank except the 37g, and that's just to get up the mess the cories make of the dead plant matter. I have no more plans to mess with the substrate, so don't worry.
Batiki nerites are small, like coronas and they have very interesting patterns. Take the stripes of a zebra nerite and scramble the lines a whole bunch in funky, wacky ways and you've got a batiki. I'll try to take some pics but they are all so so different that seeing one doesn't really give you an idea of all the possible patterns.