Chesca, it is not true to say that it normally spreads to the bones. Your father may have PCa but you have not yet had a diagnosis of that. When you know that it is PCa and have the Gleason score, following a biopsy and know about any spread following a scan you will be in a position to make judgements such as you seek. Until then you must be patient and not fear the worst when you do not have the facts.
As regards survival, your father's oncologist has no more idea than me. With advanced metastatic PCa, I have however, lasted eleven years and have some way to go. Others have not been so lucky.