Be sure and get rid of the first few gallons it makes. A recommendation should be in the reading stuff. It won't go any faster. My wife even makes me keep a entire trash can for the disposed water. Wahses clothes with it. Guessing it trashes 2 gallons for every gallon it makes.
If anything lives from the rock it'll show up later - depending on how you cycle. Some change water to keep critters living I thing. Others just let the ammonia go up high and do it's thing. That ususally knocks out inverts for the most part.
After the cycle, if you add small pieces of rock you likely get more critters depending on the rock source of course. Then, if any die-off, the exisiting cycled tank could absorb ammonia better and stuff on rock would live more easily.
If I were you, I'd consider making more swin thru areas if you can with that rock. Got some base rock in there, too, right? Maybe take it out now, let it dry and glue/putty some of that together to make some structures/arches/tunnels,etc. Inever was a fan of just having it stacked.
I also enjoy being able to clean the sides of the glass. The rock positioned that way may give you problems later. Just enuf room for a magnet or your hand and a scraper. IMO
you'll enjoy it more being able to see down the sides.
Is the rock leaning against the back glass. It's OK to.
Oy yeah, once that ammonia gets up to the 4 or 5.0 level, you can remove the shrimp. Some tie it in a mesh bag to keep it from decaying and breaking up into pieces.