Getting an empty list for tracks

The proper way to use requests might be something like this,

r = requests.get('http://developer.echonest.com/api/v4/song/search', 
                params={'api_key':api_key, 'results':1, 'artist':artist, 'title':title, 'bucket':['audio_summary', 'id:spotify', 'tracks']})

You can then get the data from your response through the json() function on the response itself,

songs = r.json()['response']['songs']

I suspect you're having problems with URL encoding, and passing in a params dictionary instead of trying to build the URL yourself is a good way to make sure you don't need to worry about it. It might also be worthwhile to install Pyen, our Python JavaScript wrapper, and use that instead.