Thanks for your query.
1) Precum is a secretion of Coper's glands located in urethra
2) It does not contain sperm at all.
3)Urine is acidic in nature hence sperm can not survive longer in urine and
any sperm in urethra get washed away with passing urine.
4) Sperms can not survive more than few hours after ejaculation.
5)Woman can not get pregnant with only precum even though it is deposited in Vagina.