For the shrimp, they will probably hide the majority of the time and might get eaten during their moult, but they're interesting and do a good clean up job. However there are different
Palaemonetes species that are freshwater, brackish, or marine, and PetSmart/Petco tend to get different species in all under the name Ghost Shrimp, so its a crap shoot whether you're getting the correct species or not. And don't forget those tetras will need at least 4 conspecifics for each species, as they are schooling.

Have fun setting up your new tank!