Nokia 8110 4G comes with 512MB RAM and 4GB internal storage. You will get practically unlimited storage for SMS.
Yes, Nokia 8110 4G does have the GPS support.
Yes, Nokia 8110 4G is a dual sim mobile phone. You can use one 4G sim card in one slot and another slot will be on the 2G network.
Yes, Nokia 8110 4G does have the FM radio.