It is very encouraging to see your zeal for the knowledge of Deen. May Allah Ta'ala increase your understanding of Islam and keep you steadfast on the journey of acquiring knowledge.
Your understanding is correct Shia books are not reliable and cannot be used by us for rulings.
The difference between sunnis and shias is an usuli (fundamental) difference.
Regarding family laws and family etiquettes I have attached the link of three books by some senior scholars.
These three books should cover the topic very well. They're all translations of the original books.
My advice is that you read these books multiple times. Finish one round and start again read them a few times so the understanding of the laws settle. This is the correct and best way to seek knowledge -to read a book multiple times.
Also there's another that I recommend to people, that has shown to have tremendous benefit of increasing Deen in one's life. The book is called Fazail A'amaal (by shaykh Zakaria Kandewlawi). I recommend you read little every day of this also.