Data Sharing Rules Without Related Lists

Data Sharing Rules Without Related Lists

Hello all, 

I have a questions to which I cannot seem to find an answer.
It is not really clear to me what data will be shared under which option when using data sharing rules.

1. Default organisation settings - you can set to private, public read only, public read/write/edit
But what about related lists, will this be also shared?

2. Data Sharing Rules
Also it is not clear to me if I make a sharing rule from one role to another will realted lists also be shared?

Finally if the answer to both questions is YES RELATED LIST WILL BE SHARED,
I am looking for a solution to Bulk Share records between users, WITHOUT related lists.
I have 25,000 records in the Account module alone, I think it is crazy if the only way to share without related list is via manual sharing.

Thank you all!
Ivan