You will need to do water changes every 1-2 weeks, but you shouldn't need to do full gravel vacuuming. Any debris on the substrate and leaves can be siphoned off without digging into the gravel. This is why I actually keep mts snails in my planted tanks; they stir the substrate for me.
There are a few different tricks for the baby shrimps, some work better than others. You can put a piece of nylon/netting over the intake side of your siphon. Personally, I use a long piece of airline tubing and a white bowl or bucket. After siphoning, I let the water settle and look for any babies that got sucked up and scoop them out and back into the tank.
And yes, if you have more than one color of cherry (neocaridina) shrimp, they will produce brown/wild coloration babies. I got away with some Red Rilli shrimp in with my sakura, but the subsequent generations are simply all red.
My shrimp tank has occasionally been home to a betta. currently it's just cherry shrimp and red ramshorns, along with a large colony of mts snails. Supposedly there are Thai micro crabs in there, but other than a shell of one 1.5 years after I put them in, there's been no sign of them.