I am planning to install odoo 10 Enterprise on premises (Ubunto...as recommended) , for 10-15 users at the beginning, but I also need to use Odoo eCommerce module.  I am worried about hosting both (ERP and eCommerce) on the same server. first for security, and second for performance and Internet speed. My questions are:

1- what is the recommend bandwidth speed to have good  performance for both?

2- if possible, how i can host the ERP in-house, and host the eCommerce in the cloud for the same Database?

thanks