I have 7 in my 10 gallon with a betta, they have been in there for a few months with no problems.
In a 14 gallon you could get 7+ they hardly have a bioload.
Feed daily, mine tend to eat the left overs of food.
They like sinking shrimp pellets alot. Mine will actually carry it around the tank with them.
If you use aquarium salt be careful since it could harm them.
For any other info use this site: http://www.theshrimpfarm.com/shrimp/snowball-shrimp.php
They don't have ghost shrimp on there but snowball shrimp have the same requirements as ghost shrimp.