odoo customer portal settings

We have three multilanguage and multicurrency websites with odoo.

Everyone is stand-alone, but after a merger we want to give our customers the following features:

- 2 websites should remain B2B (prices are visible only after login only). Sign up should be free for everybody.
Specific pricelists apply to Dealers, institutional Customers and remaining Customers. Inventory quantities visible to logged customers.

- the remaining website should be open to B2C (prices are public) even if not all products are published

- logged customers a unique login for all the 3 websites