1. proscar and propecia are the same drug, finasteride. proscar = 5mg and is usually prescribed for prostate in that strength. propecia=1mg and is prescribed for hair loss in that strength. not sure where you heard that it will fuck up your prostate, as it is prescribed to treat it.
2. the beauty of proscar is its drug definition with respect to insurance companies. propecia is not billable to insurance because by definition, it does not treat a condition deemed reimbursable by insurance. proscar on the other hand is reimbursable. it's a loophole in insurance and the difference to the consumer is about $35 a month, depending on your prescription copay. (approx $50 vs $15 copay)
3. i don't care what anyone says. finasteride affects libido in MUCH more than 5% of the administering population. so if you take proscar, expect a lower sex drive. no way to tell how much lower until you take it, effects people differently. either way, libido returns to normal when you stop taking it.
4. you can't take proscar for a couple months to "ward off" baldness. once it is started it needs to be taken once a day for life, if you expect to get anything out of it. if you care about your hair and happen to run steroids, you'll already be taking proscar, so its effects will help during and after cycle. but if you stop taking it, and assuming you show signs of male pattern baldness, the balding process will continue its course and all regrown hair will fall out within a few weeks of terminating the product.
i'm no doctor, i've gathered info over the past few years. hope that helps.