K.P.
We added a little cow's milk to the formula at a time. We learned quickly that he couldn't handle it. I have a soy baby. When I introduced the milk he started waking up at night very gassy and then the next day diapers said it all. Once I stopped the cow's milk he was fine.
As for warm or cold -- If I am traveling and have the canned soy milk my son gets it at room temp but everyday use he gets cold milk.
My sister got in the habit of warming up her sons milk and now that he is 3 every morning he request it.
Serve the temp you feel best. My son drinks his soy milk cold no problem.
Good luck.