How to automate sending email via Salesforce?

You can do this with workflow rules if you have Salesforce Enterprise or Unlimited Edition. Under Setup > App Setup > Create > Workflows & Approvals
Create a new workflow rule and then set an email alert to go out based on your criteria. For the first example you mentioned, you'd want to set your workflow rule to run on Accounts "only when a record is created" and the status = "your status here." You need to make an email template first before being able to trigger an email alert. You can do that under Setup > Administration Setup > Communication Templates > Email Templates.