Hey O pancho
I did both dwarf hair grass and HC in a 10g with DIY CO2 about a year ago. My light was just a cfl (one if those spiral Compact Fluorescent Lights) I think 24 watts, but it said it was a 75w equivalent? It was in a reflector to get the most out of it, and I got that at Cal Ranch. It was a dirt tank capped with sand, the dirt was from behind my apartment. It took a few weeks, but the HC took root and started to grow great, the hair grass seemed to take a little longer, but that could have been because I bought it from petsmart that sold it in a bag with gel stuff on the roots. Who knows. But it eventually sent runners out and started to spread. But it seems to me that the nature of the plant prevent it from getting "thick" like a carpet. Maybe if there were a bunch if runners overlapping.
With that said, I say try HC. Your ecocomplete substrate should work great. I just started a tank a few months ago, planted HC, and it's thrived. Just added CO2 yesterday, so it might take off even faster. Have a gander at my tank journal... The red cherry shrimps you asked about are in there.
And if you're planning on getting some RCS and wanna have them breed, put a sponge or nylon over your filter intake so the little dudes don't get sucked up.