That's a huge topic. In fact, some the information you asked for isn't known at this time. No one really knows how different hormones break down and how deer use them in communication.
Urine is sterile in the bladder, but as it is excreted from the body it begins to pick up bacteria, and urine is a fantastic bacterial growth medium. In fact, when bucks urinate over their tarsal glands, the urine is being used as a bacterial growth medium. The tarsal gland itself does not produce "smells", it just produces the required ingredients for the retention and growth of a wide variety of bacteria. These bacteria then produce the rut "smells" as byproducts of their life-cycle. And research being done at UGA is finding that the older a buck is, the more varieties of bacteria live on their tarsals, hence the more smells produced. This is probably how bucks and does can communicate age/dominance/health through these type of chemical communications.
Studies at UGA also found that whatever "estrus" chemicals bucks pick up on from doe urine, it is not in the urine itself. It is picked up as the urine is excreted across the genitals. In tests, UGA researchers found that urine collected using catheters directly from the bladder of estrus doe elicited no response from bucks. Yet urine captured as it was excreted did. However, as soon as urine makes contact with the air, it begins to break down, with each volatile component breaking down at a different rate (and that is how bucks know which way to trail a doe. Their brains can "measure" the tiny differences in the amount of volatile components, deciphering which direction the scent trail is "freshest"). With commercial "doe-in-heat" scents, unless the urine was captured via catheter and never exposed to the air, the urine is breaking down even if it is later sealed in an airtight container. This means the urine will smell "old" to a deer as it continues to break down inside the sealed container. Yet if they capture the urine with catheters to prevent break-down, they're not getting the essential "estrus" scents that are only picked up during excretion.
