Is prostate cancer preventable?

Maybe. There have been numerous studies on prostate cancer prevention. There are two related drugs, Finasteride and dutasteride, which were shown in large trials, to reduce the risk of developing prostate cancer by about 25%. The fda did not approve these drugs for cancer prevention because a higher percentage of the cancers which did develop were high grade, or more aggressive.
No, but... Prostate cancer is not the male ovarian cancer, but prostate, breast and ovarian cancers are all hormone-related cancers which have some similarities. In fact, some families which share one of the known breast cancer genes are also at higher risk of prostate cancer, so i always pay attention to the family history when determining risk.
No. Prostate cancer is multifactorial. It can occur sporadically or be familial (in the genes). Even if there isma family history of prostate cancer, screening should be intensified but there is still no way to prevent the cancer.