Oh no, poor shrimp! Doctor might have harrassed him to death as well though, Betta's are notorious for eating shrimp unfortunately unless you have a sort of jungle in your tank to give lots of spaces for the shrimp to hide and get away from the Betta. But yeah that's the good thing about Ghost Shrimp, they are inexpensive so it's a good way to test out your Betta to see if they are too aggressive to have other shrimp in there. But yes, shrimp are also delicate and need to be acclimated very well. I use the Drip method to acclimate shrimp when I get them.
As for plants anything fast growing would be good; anacharis, hornwort, water wisteria, water sprite, rotala and ludwigia. Java ferns are great too, I've had good luck with mine, they're pretty tough to kill. I got my Java Moss online, actually most of my plants came from online.
But my faves are Java Fern, Water Wisteria, Water Sprite and Vallisneria.