Gmail is so so good. You get 1000 MB of free storage, so no need to delete. It roups messages together in coversations so youw inbox makes more sense, and you can search all your mail for a keyword, and since you never delete you can find everything.
And best of all it is as quick as google, so no waiting for inbox to appear...
It doesnt really work like that. It doesnt build a profile, it just looks at keywords on the page and finds possible sites that match. Not like spyware or anything, and totally safe.