I stopped taking birth control a month ago only after using it for 4 months how soon can I get prenant?

Almost immediately. Ovulation returns in about 2-4 weeks after stopping the birth control pill. You need not wait to try although there is some data suggesting twins in the first month after stopping. If you want information about menstruation and ovulation see my vimeo account: cascade fertility and michael opsahl md.
Depends. It is safe now - if you are trying to get pregnant - start keeping track of your periods, eat healthy, don't smoke or drink alcohol and take a prenatal vitamin.