Yay for shrimpies! They LOVE moss, I have the Christmas moss and Java moss, I'd say that is ultimately their favorite plant, plus its usually where the shrimplets hide. Other than that I haven't noticed any particular plant being a favorite, they love cleaning out the little squares on the lace leaf, which rocks! But they wander all over the tank and the surface of the water. I'm not positive what plant it is, I had Lauraf ID it once, I forget the name...but anyway it floats on top of the water I don't have it planted, and they love that because they can sit up there and get food from the surface. I think the java fern is also another favorite, I have an anubias congensis, but they don't hang out on it much nor the aponogeton ulvaceus. I think they ultimately like bushy plants, that is where I see mine most often.
They also LOVE blood worms and brine shrimp, but blood worms for sure!
And not that I should, but I stick my hands in my tank all the time, haha. Either trimming or catching a floating leaf, cleaning something...moving something. I try to avoid that though, but my shrimp actually like to come over to my hand like "Hey what's this?! Food?!" Then I stick my finger at them and they jump away. Although I'd definitely wait until they are acclimated a bit before sticking your hands in a bunch, just so they can decrease any stress and get use to the new place!
But really, shrimp are SO fun and not much is really required. Especially because you have such well established tanks and so much knowledge!
edit: I looked and she had said it was whorled pennywort that I have, that's the surface floater in the tank!