Can we dynamically generate the body of an Email Template?

How can we dynamically insert things in the Body of an Email Template

What are Extension Controller's and how can we create them?

Can we invoke more than one controller in a vf page?

As reports can be added to dashboards but what is the limit?How many reports can be added to a dashboard?

What are the properties of Process Builder that differentiates it from Workflow?

Marketing is also a part of Sales so how it differ in case of Clouds in Salesforce?

SaaS(Software as a Service) and PaaS(Platform as a Service)