Regarding the second point,to create DB users a grant permissions, you can connect to the instance using the SQL Server Management Studio if you have window as OS, if not, you can use the “sqlcmd” tool , in the document “Install sqlcmd and bcp the SQL Server command-line tools on Linux” or mac you can see the steps to install it. Then you have to follow the instructions of the document “Install the Cloud SQL Proxy client on your local machine” to set up the connection to the instance.
Once you are connected to the instance, you can add users to the database using the SQL Server Management Studio console or using this command:
- Creates the login username with password 'password'.
CREATE LOGIN user_name
WITH PASSWORD = 'password';
GO
-- Creates a database user for the login created above.
CREATE USER username FOR LOGIN username;
GO
You can see more detail of the previous script on the link.
Once you have created the users, you can add one of the Fixed-Database Roles listed in the link.If you are using the command line you can use the following command:
EXE SP_ADDROLEMEMBER ‘role_name’, ‘user_name’
You can see more detail about adding roles in the link.
Regarding the first point, I think that you can use the same way described in the this response