It is true that ideally you want a softer, sandy substrate for corys. If you’ve ever seen them dig through it searching for food, you’ll understand why and never want to deprive them of that. It’s second only to their wiggling when it comes to their cute behaviors…With regard to the honey gourami and small shrimp: it may work, but it may not. Make sure there’s plenty of cover. I know some who’ve kept them together with little problems and some who’ve had their gourami eat the shrimp. I used to have a pair of blue rams that peacefully coexisted with cherry shrimp, until I added another pair of rams which apparently taught the first pair that they were food…Another suggestion would be a dozen neons, a honey gourami and some amano shrimp- they’re too big for the gourami to mess with. Otos would work too.