hi France
never tried to get to Granada before, but if you catch the frequent trains from arroyo de meil about 10mins walk depending where you are for about 3 euros that will take you to Malaga where you can catch the fast train.
you must make a visit to the city of Malaga its lovely
Ive been to Benalmadena 3 times the harbour is beautiful and the place for eating is very cheap and paloma park is stunning (but beware of people selling scratch cards just walk on its a big scam)if you click on the link below and join up (its free) any questions regarding transport or the surrounding areas will be answered very quickly
enjoy your stay in Benal
http://benalmadena.vforums.co.uk/