Ok first off I would highly suggest you treat your newt with something. . . if not the Melafix then perhaps another aquatic anti fungal medicine for the sake of preventing infection.If you have a local Petsmart or Petco I would suggest going there.
To the best of my knowledge most newts/salamanders of the same species can be kept together. However in this case it doesn't seem to be working out. If you are using a 10 gallon tank you might try a tank divider which can also be picked up at Petsmart or Petco, but with their ability to climb that may not work. You could also pick up a 5 gallon terrarium tank (which is not too spendy). I would suggest you seperate them as soon as possible though.
As for the type of shrimp. . . I am no help. Other members should be along to offer further help in that department. When in doubt stick with what is safe. . . newt pellets, chopped earth worms, small crickets, etc. 
Icy