About the cottage: Diletta's cottage is very near circus maximo metro station from there you could walk to the colosseum and forum.
Maybe a newer picture of the cottage is necessary to avoid some disappointment.
About Diletta: arriving at Otiense train station I was told by her to send her a text message when I arrived there, I call her upon arrival, when I ask her which direction to go out from the train station she couldn't tell me which exit and she advised me to take a taxi from there (cost 15 euros).
She then received us and show us the cottage and leave us the key. That's the first and last time we saw her on our 5 days stay in her cottage and you couldn't also leave your luggage at her place if you have a later flight.