Mário's mother was very kind and understanding and gave me lots of useful advice about travel and what to see etc. The nearest Subte or underground station is Dorrego, about a 10 minute walk away, and this is on Av Correntes, the main artery into BA.
There are shops and places to eat nearby. For me, the streets are a little noisy (cars passing, and the train nearby), so with the windows open I didn't sleep too well at first.
However, all in all it's quite comfortable and there's a nice balcony where you can sit outside and have a beer.