Have to say you need a heavy investment in Amazon for the Echo to be of any real use. Without it it will tell you jokes and facts and the weather\news but not much else.
You need Prime @£70 a year which gives you access to 2 million music tracks, you can also load up to 250 of your own tracks as well
Then there are more Amazon options, Music unlimited (40 million tracks) 7.99 PM, Kindle unlimited if you want the Echo to read books (it will read compatible ones you own in your kindle library) 7.99 PM
You can also pay £22 a year and upload 250,000 of you own tracks into Amazon music, pretty sure you will need Prime for this though.
Then there is the 3rd part stuff that costs as well. I'm getting a lot out of mine and will probably get another this week for the kitchen but so far I've spent the following before the cost of the Echo.
Hive £250
Harmony £200 (this was the most expensive model and could be done cheaper)
Prime £70
Really like it though
In terms of listening I think it does that all the time ,but its not recording anything until you say the trigger word "Alexa," then a command, all of this is kept for "improving" the service but you can delete it all if you want.