I treated the shrimp much like I treat my fish. I suspect they probably are a little hardier at handling changes, but wouldn't count on that. I'd release the shrimp into as thickly vegetated area as your pond has or if you have an area with large rocks with crevices, that would be another option. How many did you order?

Personally, I am not a fan of the gambusia, but I will bet they'll quickly establish in your pond even with an established fish population if the western species is anything like the eastern one. They are amazingly predator resistant.