Yes I'm sure you can do this, they sell the daily tickets from a the tobacconist kiosks as I recall - pretty sure last time I was in Rome I bought a daily Metro/Bus combined ticket after getting of the train in from the airport - was fairly reasonably priced
No idea about the route maps, but I think there were maps on most stops.
You can buy a ticket in the Termini which is a kind of Central Station and where the airport train stops for E4.00. We bought ours from a machine. It gives you unlimited travel on the bus, tram and underground for the day.
all the metro stations have ticket machines which are quiet easy to use, you have a choice of 75 minute ticket or 24 hour €4 or monthly and so on, i cant remember if they are in english but there are station people around if you need help
Last year, an American friend was on her first ever bus ride in Rome and was fined 50 Euro I think for not validating her ticket - she honestly didn't know she had to..