How Ads Process Work ?

Greetings -
I setup my Ads to expire after 7 days, but I noticed that the Ads were completely deleted after 7 days.. I was under the impression that the members can reactivate their Ads without recreating them from scratch - is this how the Ads process supposed to work ?

Also, I see this option in Admin that says:  "Automatic advertisements activation after adding" - What advertisements are they referring to ? is this mean the users Ads will be displayed on the front page?

I have my own advertisement system which has nothing to do with the Ads, not sure what this advertisment option within Ads is used for ?

Your input is much appreciated.. Thx.

Cheers,