Hi Guys,
I have visited Digha few times, first time I went there as just a curiosity, then after that I have been there just because of peer pressure and not availability of any beach destination near Kolkata. The beaches are dirty and well under maintained.
The location can be accessed via train and bus from Kolkata, but the best way to visit there is via own or rented car, you will require a car to visit nearby places. Buses and trains are frequently available.
In local site seeing, mandarmony beach is there, new Digha beach and Tajpur beach is there but it at a far distance. Other than that you can have local sea food.
Hotels and accommodations are available in every range, best hotels are present in Mandarmony, most of the hotels there are sea facing. Few of them have private beaches also.
Regarding safety I will say swim in the sea at your own risk, there are not much rescue arrangements. Roaming in the town is relatively safe but avoid going out at night.