Customers email template & mass email

-- HikaShop version -- : 2.4.0
-- Joomla version -- : 3.4.1
-- PHP version -- : 5.4.40
-- Browser(s) name and version -- : Chrome

Hi,

2 questions:

1- I've looked everywhere but can't seems to find how to modify the template of the email sent to our customers.
I need to add banner, logos, change CSS? colours, etc.

2- How can I send an email to all user to update their password?
We are migrating to Hikashop. We created all customer's account and default password be we would like them to update their informations.

Thanks!