I too have been researching Peter Cassidy. But I am stuck here and can not seem to get my research past the east coast of the us. Peter would be my third great grandfather.
Please search for the San Joaquin county historical record of Bernard Cassidy who is his son. Some of the information in your post is included in this record but there is more.
We might be able to help each other or might had a historical connection
Thanks for the post
Michael B Cassidy