What newsletter? What is email marketing? what is autoresponder? RSS is the same as feedburner?

I use wordpress in my two sites. and I'm super confused when it comes to mail markekting:
What newsletter?
What is email marketing?
what is autoresponder?
RSS is the same as feedburner?
Feedburner is an autoresponder or an RSS manager?
mailpoet does everything the Egoi do or are different services? to wordpress which is the most suitable? I want to write an email with any notification to everyone at once (which name it, newsletter? RSS?) ... want three things in my blog .. people to be notified with any new post. and I want people to sign up on a product of interest of them to receive pre-programmed messages and divided into daily parts (that looks like it is autoreponder feature) ... divide the delivery of a letter of camapanha .. sales of a particular product and or seviço. third thing .... I want to send a message to all subscribers one fell swoop.
I have one in my RSS blogwordpress?
I have an autoresponder on my blog?
should have a newsletter on my blog?
one of these is dispensable or essential in order to replace the other? or must have 3? what the best wordpress tools for me to take that 3 features?
There is a tool that brings me these three resources?