Below is a link to a website that has hundreds of books discussing Shi'a Islam:

https://www.al-islam.org/

From the above website, I am linking a few books that might interest you and answer your questions but you are free to look at the main website and search for other books that would answer your questions:

https://www.al-islam.org/al-murajaat-abd-al-husayn-sharaf-al-din-al-musawi

https://www.al-islam.org/shiism-imamate-and-wilayat-sayyid-muhammad-rizvi

https://www.al-islam.org/discovering-shii-islam-mohammad-ali-shomali

https://www.al-islam.org/lets-learn-about-imamate-naser-makarem-shirazi

https://www.al-islam.org/brother-prophet-muhammad-imam-ali-shaykh-muhammad-jawad-chirri

Since it is Muharram where we commemorate the death of the grandson of the Prophet, I have copied two links below relating to the event and it's analysis:

https://www.al-islam.org/revolution-imam-husayn-mansour-leghaei

https://www.al-islam.org/lohoof-sighs-sorrow-sayyid-ibn-tawus