You can do it but 2 thoughts:
One, get the 98% fat free version, it will dry better and faster.
Two...consider getting the lower sodium version as well (Healthy Request), drying salty items can ramp up the flavor bad.

And yes you can just add hot water and it will come back. If you want it creamier add in dry milk as well.

If you want to try making a homemade soup this tomato soup is good smile
http://www.trailcooking.com/recipes/creamy-tomato-soup
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