One can use glycerine or propylene glycol as an anti-freeze in real cold weather. Also, one can add a little plain pickling salt which works as an anti-freeze and preservative too.
As for putting glands in the urine, one has made a lure when that is done. Personally I would rather use the lure down the hole and plain urine on the backing as natural attraction, suspicion remover and final touch to a set. I doubt that squirting or spraying would make that much difference but being that i'm not sure I would rather simulate a natural application by the animal of a small squirt onto the backing. Ace